The ssl_sock.c file contains a lot of macros and structure definitions
that should be in a .h. Move them to the more appropriate
types/ssl_sock.h file.
Make use of ssl_sock_register_msg_callback(). Function ssl_sock_msgcbk()
is now split into two dedicated functions for heartbeat and clienthello.
They are both registered by using a new callback mechanism for SSL/TLS
protocol messages.
This patch adds the ability to register callbacks for SSL/TLS protocol
messages by using the function ssl_sock_register_msg_callback().
All registered callback functions will be called when observing received
or sent SSL/TLS protocol messages.
aes_gcm_dec is independent of the TLS implementation and fits better
in sample.c file with others hash functions.
[Cf: I slightly updated this patch to move aes_gcm_dec converter in sample.c
instead the new file crypto.c]
Reviewed-by: Tim Duesterhus <tim@bastelstu.be>
For 6 years now we've been seeing a warning suggesting to set dh-param
beyond 1024 if possible when it was not set. It's about time to do it
and get rid of this warning since most users seem to already use 2048.
It will remain possible to set a lower value of course, so only those
who were experiencing the warning and were relying on the default value
may notice a change (higher CPU usage). For more context, please refer
to this thread :
https://www.mail-archive.com/haproxy@formilux.org/msg37226.html
This commit removes a big chunk of code which happened to be needed
exclusively to figure if it was required to emit a warning or not :-)
A sample must always have a session defined. Otherwise, it is a bug. So it is
unnecessary to test if it is defined when called from a health checks context.
This patch fixes the issue #616.
SSL sample fetches acting on the server connection can now be called from any
sample expression or log-format string in a tcp-check based ruleset. ssl_bc and
ssl_bc_* sample fetches are concerned.
After we call SSL_SESSION_get_id(), the length of the id in bytes is
stored in "len", which was never checked. This could cause unexpected
behavior when using the "ssl_fc_session_id" or "ssl_bc_session_id"
fetchers (eg. the result can be an empty value).
The issue was introduced with commit 105599c ("BUG/MEDIUM: ssl: fix
several bad pointer aliases in a few sample fetch functions").
This patch must be backported to 2.1, 2.0, and 1.9.
Building without threads now shows this warning:
src/ssl_sock.c: In function 'cli_io_handler_commit_cert':
src/ssl_sock.c:12121:24: warning: unused variable 'bind_conf' [-Wunused-variable]
struct bind_conf *bind_conf = ckchi->bind_conf;
^~~~~~~~~
This is because the variable is needed only to unlock the structure, and
the unlock operation does nothing in this case. Let's mark the variable
__maybe_unused for this, but it would be convenient in the long term if
we could make the thread macros pretend they consume the argument so that
this remains less visible outside.
No backport is needed.
The options and directives related to the configuration of checks in a backend
may be defined after the servers declarations. So, initialization of the check
of each server must not be performed during configuration parsing, because some
info may be missing. Instead, it must be done during the configuration validity
check.
Thus, callback functions are registered to be called for each server after the
config validity check, one for the server check and another one for the server
agent-check. In addition deinit callback functions are also registered to
release these checks.
This patch should be backported as far as 1.7. But per-server post_check
callback functions are only supported since the 2.1. And the initcall mechanism
does not exist before the 1.9. Finally, in 1.7, the code is totally
different. So the backport will be harder on older versions.
This options is used to force a non-SSL connection to check a SSL server or to
invert a check-ssl option inherited from the default section. The use_ssl field
in the check structure is used to know if a SSL connection must be used
(use_ssl=1) or not (use_ssl=0). The server configuration is used by default.
The problem is that we cannot distinguish the default case (no specific SSL
check option) and the case of an explicit non-SSL check. In both, use_ssl is set
to 0. So the server configuration is always used. For a SSL server, when
no-check-ssl option is set, the check is still performed using a SSL
configuration.
To fix the bug, instead of a boolean value (0=TCP, 1=SSL), we use a ternary value :
* 0 = use server config
* 1 = force SSL
* -1 = force non-SSL
The same is done for the server parameter. It is not really necessary for
now. But it is a good way to know is the server no-ssl option is set.
In addition, the PR_O_TCPCHK_SSL proxy option is no longer used to set use_ssl
to 1 for a check. Instead the flag is directly tested to prepare or destroy the
server SSL context.
This patch should be backported as far as 1.8.
Documentation states that default settings for ssl server options can be set
using either ssl-default-server-options or default-server directives. In practice,
not all ssl server options can have default values, such as ssl-min-ver, ssl-max-ver,
etc..
This patch adds the missing ssl options in srv_ssl_settings_cpy() and srv_parse_ssl(),
making it possible to write configurations like the following examples, and have them
behave as expected.
global
ssl-default-server-options ssl-max-ver TLSv1.2
defaults
mode http
listen l1
bind 1.2.3.4:80
default-server ssl verify none
server s1 1.2.3.5:443
listen l2
bind 2.2.3.4:80
default-server ssl verify none ssl-max-ver TLSv1.3 ssl-min-ver TLSv1.2
server s1 1.2.3.6:443
This should be backported as far as 1.8.
This fixes issue #595.
This option activate the feature introduce in commit 16739778:
"MINOR: ssl: skip self issued CA in cert chain for ssl_ctx".
The patch disable the feature per default.
When trying to insert a new certificate into a directory with "add ssl
crt-list", no check were done on the path of the new certificate.
To be more consistent with the HAProxy reload, when adding a file to
a crt-list, if this crt-list is a directory, the certificate will need
to have the directory in its path.
Allowing the use of SSL options and filters when adding a file in a
directory is not really consistent with the reload of HAProxy. Disable
the ability to use these options if one try to use them with a directory.
When reading a crt-list file, the SSL options betweeen square brackets
are parsed, however the calling function sets the ssl_conf ptr to NULL
leading to all options being ignored, and a memory leak.
This is a remaining of the previous code which was forgotten.
This bug was introduced by 97b0810 ("MINOR: ssl: split the line parsing
of the crt-list").
Create a ckch_store_new() function which alloc and initialize a
ckch_store, allowing us to remove duplicated code and avoiding wrong
initialization in the future.
Bug introduced by d9d5d1b ("MINOR: ssl: free instances and SNIs with
ckch_inst_free()").
Upon an 'commit ssl cert' the HA_RWLOCK_WRUNLOCK of the SNI lock is done
with using the bind_conf pointer of the ckch_inst which was freed.
Fix the problem by using an intermediate variable to store the
bind_conf pointer.
Replace ckchs_free() by ckch_store_free() which frees the ckch_store but
now also all its ckch_inst with ckch_inst_free().
Also remove the "ckchs" naming since its confusing.
In 'commit ssl cert', instead of trying to regenerate a list of filters
from the SNIs, use the list provided by the crtlist_entry used to
generate the ckch_inst.
This list of filters doesn't need to be free'd anymore since they are
always reused from the crtlist_entry.
Use the refcount of the SSL_CTX' to free them instead of freeing them on
certains conditions. That way we can free the SSL_CTX everywhere its
pointer is used.
When deleting the previous SNI entries with 'set ssl cert', the old
SSL_CTX' were not free'd, which probably prevent the completion of the
free of the X509 in the old ckch_store, because of the refcounts in the
SSL library.
This bug was introduced by 150bfa8 ("MEDIUM: cli/ssl: handle the
creation of SSL_CTX in an IO handler").
Must be backported to 2.1.
The crtlist_load_cert_dir() caches the directory name without trailing
slashes when ssl_sock_load_cert_list_file() tries to lookup without
cleaning the trailing slashes.
This bug leads to creating the crtlist twice and prevents to remove
correctly a crtlist_entry since it exists in the serveral crtlists
created by accident.
Move the trailing slashes cleanup in ssl_sock_load_cert_list_file() to
fix the problem.
This bug was introduced by 6be66ec ("MINOR: ssl: directories are loaded
like crt-list")
Delete a certificate store from HAProxy and free its memory. The
certificate must be unused and removed from any crt-list or directory.
The deletion doesn't work with a certificate referenced directly with
the "crt" directive in the configuration.
Bundles are deprecated and can't be used with the crt-list command of
the CLI, improve the error output when trying to use them so the users
can disable them.
The cli_parse_del_crtlist() does unlock the ckch big lock, but it does
not lock it at the beginning of the function which is dangerous.
As a side effect it let the structures locked once it called the unlock.
This bug was introduced by 0a9b941 ("MINOR: ssl/cli: 'del ssl crt-list'
delete an entry")
Issue #574 reported an unclear error when trying to open a file with not
enough permission.
[ALERT] 096/032117 (835) : parsing [/etc/haproxy/haproxy.cfg:54] : 'bind :443' : error encountered while processing 'crt'.
[ALERT] 096/032117 (835) : Error(s) found in configuration file : /etc/haproxy/haproxy.cfg
[ALERT] 096/032117 (835) : Fatal errors found in configuration.
Improve the error to give us more information:
[ALERT] 097/142030 (240089) : parsing [test.cfg:22] : 'bind :443' : cannot open the file 'kikyo.pem.rsa'.
[ALERT] 097/142030 (240089) : Error(s) found in configuration file : test.cfg
[ALERT] 097/142030 (240089) : Fatal errors found in configuration.
This patch could be backported in 2.1.
The dump and show ssl crt-list commands does the same thing, they dump
the content of a crt-list, but the 'show' displays an ID in the first
column. Delete the 'dump' command so it is replaced by the 'show' one.
The old 'show' command is replaced by an '-n' option to dump the ID.
And the ID which was a pointer is replaced by a line number and placed
after colons in the filename.
Example:
$ echo "show ssl crt-list -n kikyo.crt-list" | socat /tmp/sock1 -
# kikyo.crt-list
kikyo.pem.rsa:1 secure.domain.tld
kikyo.pem.ecdsa:2 secure.domain.tld
Delete an entry in a crt-list, this is done by iterating over the
ckch_inst in the crtlist_entry. For each ckch_inst the bind_conf lock is
held during the deletion of the sni_ctx in the SNI trees. Everything
is free'd.
If there is several entries with the same certificate, a line number
must be provided to chose with entry delete.
Initialize fcount to 0 when 'add ssl crt-list' does not contain any
filters. This bug can lead to trying to read some filters even if they
doesn't exist.
Add the support for filters and SSL options in the CLI command
"add ssl crt-list".
The feature was implemented by applying the same parser as the crt-list
file to the payload.
The new options are passed to the command as a payload with the same
format that is suppported by the crt-list file itself, so you can easily
copy a line from a file and push it via the CLI.
Example:
printf "add ssl crt-list localhost.crt-list <<\necdsa.pem [verify none allow-0rtt] localhost !www.test1.com\n\n" | socat /tmp/sock1 -
In order to reuse the crt-list line parsing in "add ssl crt-list",
the line parsing was extracted from crtlist_parse_file() to a new
function crtlist_parse_line().
This function fills a crtlist_entry structure with a bind_ssl_conf and
the list of filters.
The new 'add ssl crt-list' command allows to add a new crt-list entry in
a crt-list (or a directory since they are handled the same way).
The principle is basicaly the same as the "commit ssl cert" command with
the exception that it iterates on every bind_conf that uses the crt-list
and generates a ckch instance (ckch_inst) for each of them.
The IO handler yield every 10 bind_confs so HAProxy does not get stuck in
a too much time consuming generation if it needs to generate too much
SSL_CTX'.
This command does not handle the SNI filters and the SSL configuration
yet.
Example:
$ echo "new ssl cert foo.net.pem" | socat /tmp/sock1 -
New empty certificate store 'foo.net.pem'!
$ echo -e -n "set ssl cert foo.net.pem <<\n$(cat foo.net.pem)\n\n" | socat /tmp/sock1 -
Transaction created for certificate foo.net.pem!
$ echo "commit ssl cert foo.net.pem" | socat /tmp/sock1 -
Committing foo.net.pem
Success!
$ echo "add ssl crt-list one.crt-list foo.net.pem" | socat /tmp/sock1 -
Inserting certificate 'foo.net.pem' in crt-list 'one.crt-list'......
Success!
$ echo "show ssl crt-list one.crt-list" | socat /tmp/sock1 -
# one.crt-list
0x55d17d7be360 kikyo.pem.rsa [ssl-min-ver TLSv1.0 ssl-max-ver TLSv1.3]
0x55d17d82cb10 foo.net.pem
The crtlist_entry structure use a pointer to the store as key.
That's a problem with the dynamic update of a certificate over the CLI,
because it allocates a new ckch_store. So updating the pointers is
needed. To achieve that, a linked list of the crtlist_entry was added in
the ckch_store, so it's easy to iterate on this list to update the
pointers. Another solution would have been to rework the system so we
don't allocate a new ckch_store, but it requires a rework of the ckch
code.
When updating a ckch_store we may want to update its pointer in the
crtlist_entry which use it. To do this, we need the list of the entries
using the store.
The instances were wrongly inserted in the crtlist entries, all
instances of a crt-list were inserted in the last crt-list entry.
Which was kind of handy to free all instances upon error.
Now that it's done correctly, the error path was changed, it must
iterate on the entries and find the ckch_insts which were generated for
this bind_conf. To avoid wasting time, it stops the iteration once it
found the first unsuccessful generation.
In order to be able to add new certificate in a crt-list, we need the
list of bind_conf that uses this crt-list so we can create a ckch_inst
for each of them.
First: self issued CA, aka root CA, is the enchor for chain validation,
no need to send it, client must have it. HAProxy can skip it in ssl_ctx.
Second: the main motivation to skip root CA in ssl_ctx is to be able to
provide it in the chain without drawback. Use case is to provide issuer
for ocsp without the need for .issuer and be able to share it in
issuers-chain-path. This concerns all certificates without intermediate
certificates. It's useless for BoringSSL, .issuer is ignored because ocsp
bits doesn't need it.
SSL_CTX_set1_chain is used for openssl >= 1.0.2 and a loop with
SSL_CTX_add_extra_chain_cert for openssl < 1.0.2.
SSL_CTX_add_extra_chain_cert exist with openssl >= 1.0.2 and can be
used for all openssl version (is new name is SSL_CTX_add0_chain_cert).
This patch use SSL_CTX_add_extra_chain_cert to remove any #ifdef for
compatibilty. In addition sk_X509_num()/sk_X509_value() replace
sk_X509_shift() to extract CA from chain, as it is used in others part
of the code.
This bug was introduced by 85888573 "BUG/MEDIUM: ssl: chain must be
initialized with sk_X509_new_null()". No need to set find_chain with
sk_X509_new_null(), use find_chain conditionally to fix issue #516.
This bug was referenced by issue #559.
[wla: fix some alignment/indentation issue]
Fix a potential NULL dereference in "show ssl cert" when we can't
allocate the <out> trash buffer.
This patch creates a new label so we could jump without trying to do the
ci_putchk in this case.
This bug was introduced by ea987ed ("MINOR: ssl/cli: 'new ssl cert'
command"). 2.2 only.
This bug was referenced by issue #556.
Fix a memory leak that could happen upon a "show ssl cert" if notBefore:
or notAfter: failed to extract its ASN1 string.
Introduced by d4f946c ("MINOR: ssl/cli: 'show ssl cert' give information
on the certificates"). 2.2 only.
In `crtlist_dup_filters()` add the `1` to the number of elements instead of
the size of a single element.
This bug was introduced in commit 2954c478eb,
which is 2.2+. No backport needed.
In `ckch_inst_sni_ctx_to_sni_filters` use `calloc()` to allocate the filter
array. When the function fails to allocate memory for a single entry the
whole array will be `free()`d using free_sni_filters(). With the previous
`malloc()` the pointers for entries after the failing allocation could
possibly be a garbage value.
This bug was introduced in commit 38df1c8006,
which is 2.2+. No backport needed.
The CLI command "new ssl cert" allows one to create a new certificate
store in memory. It can be filed with "set ssl cert" and "commit ssl
cert".
This patch also made a small change in "show ssl cert" to handle an
empty certificate store.
Multi-certificate bundles are not supported since they will probably be
removed soon.
This feature alone is useless since there is no way to associate the
store to a crt-list yet.
Example:
$ echo "new ssl cert foobar.pem" | socat /tmp/sock1 -
New empty certificate store 'foobar.pem'!
$ printf "set ssl cert foobar.pem <<\n$(cat localhost.pem.rsa)\n\n" | socat /tmp/sock1 -
Transaction created for certificate foobar.pem!
$ echo "commit ssl cert foobar.pem" | socat /tmp/sock1 -
Committing foobar.pem
Success!
$ echo "show ssl cert foobar.pem" | socat /tmp/sock1 -
Filename: foobar.pem
[...]
There is a memleak of the entry structure in crtlist_load_cert_dir(), in
the case we can't stat the file, or this is not a regular file. Let's
move the entry allocation so it's done after these tests.
Fix issue #551.
A memory leak happens in an error case when ckchs_load_cert_file()
returns NULL in crtlist_parse_file().
This bug was introduced by commit 2954c47 ("MEDIUM: ssl: allow crt-list caching")
This patch fixes bug #551.
Implement 2 new commands on the CLI:
show ssl crt-list [<filename>]: Without a specified filename, display
the list of crt-lists used by the configuration. If a filename is
specified, it will displays the content of this crt-list, with a line
identifier at the beginning of each line. This output must not be used
as a crt-list file.
dump ssl crt-list <filename>: Dump the content of a crt-list, the output
can be used as a crt-list file.
Note: It currently displays the default ssl-min-ver and ssl-max-ver
which are potentialy not in the original file.
The commit 6be66ec ("MINOR: ssl: directories are loaded like crt-list")
broke the directory loading of the certificates. The <crtlist> wasn't
filled by the crtlist_load_cert_dir() function. And the entries were
not correctly initialized. Leading to a segfault during startup.
Generate a directory cache with the crtlist and crtlist_entry structures.
With this new model, directories are a special case of the crt-lists.
A directory is a crt-list which allows only one occurence of each file,
without SSL configuration (ssl_bind_conf) and without filters.
The crtlist structure defines a crt-list in the HAProxy configuration.
It contains crtlist_entry structures which are the lines in a crt-list
file.
crt-list are now loaded in memory using crtlist and crtlist_entry
structures. The file is read only once. The generation algorithm changed
a little bit, new ckch instances are generated from the crtlist
structures, instead of being generated during the file loading.
The loading function was split in two, one that loads and caches the
crt-list and certificates, and one that looks for a crt-list and creates
the ckch instances.
Filters are also stored in crtlist_entry->filters as a char ** so we can
generate the sni_ctx again if needed. I won't be needed anymore to parse
the sni_ctx to do that.
A crtlist_entry stores the list of all ckch_inst that were generated
from this entry.
Pass a pointer to the struct ckch_inst to the ssl_sock_load_ckchs()
function so we can manipulate the ckch_inst from
ssl_sock_load_cert_list_file() and ssl_sock_load_cert().
These are mostly comments in the code. A few error messages were fixed
and are of low enough importance not to deserve a backport. Some regtests
were also fixed.
In order to store and cache the directory loading, the directory loading
was separated from ssl_sock_load_cert() and put in a new function
ssl_sock_load_cert_dir() to be more readable.
This patch only splits the function in two.
Since commit 244b070 ("MINOR: ssl/cli: support crt-list filters"),
HAProxy generates a list of filters based on the sni_ctx in memory.
However it's not always relevant, sometimes no filters were configured
and the CN/SAN in the new certificate are not the same.
This patch fixes the issue by using a flag filters in the ckch_inst, so
we are able to know if there were filters or not. In the late case it
uses the CN/SAN of the new certificate to generate the sni_ctx.
note: filters are still only used in the crt-list atm.
There's a build error reported here:
c9c6cdbf9c/checks
It's just caused by an inconditional assignment of tmp_filter to
*sni_filter without having been initialized, though it's harmless because
this return pointer is not used when fcount is NULL, which is the only
case where this happens.
No backport is needed as this was brought today by commit 38df1c8006
("MINOR: ssl/cli: support crt-list filters").
It was only possible to go down from the ckch_store to the sni_ctx but
not to go up from the sni_ctx to the ckch_store.
To allow that, 2 pointers were added:
- a ckch_inst pointer in the struct sni_ctx
- a ckckh_store pointer in the struct ckch_inst
Generate a list of the previous filters when updating a certificate
which use filters in crt-list. Then pass this list to the function
generating the sni_ctx during the commit.
This feature allows the update of the crt-list certificates which uses
the filters with "set ssl cert".
This function could be probably replaced by creating a new
ckch_inst_new_load_store() function which take the previous sni_ctx list as
an argument instead of the char **sni_filter, avoiding the
allocation/copy during runtime for each filter. But since are still
handling the multi-cert bundles, it's better this way to avoid code
duplication.
When building with DEBUG_STRICT, there are still some BUG_ON(events&event_type)
in the subscribe() code which are not welcome anymore since we explicitly
permit to wake the caller up on readiness. This causes some regtests to fail
since 2c1f37d353 ("OPTIM: mux-h1: subscribe rather than waking up at a few
other places") when built with this option.
No backport is needed, this is 2.2-dev.
It's only available for bind line. "ca-verify-file" allows to separate
CA certificates from "ca-file". CA names sent in server hello message is
only compute from "ca-file". Typically, "ca-file" must be defined with
intermediate certificates and "ca-verify-file" with certificates to
ending the chain, like root CA.
Fix issue #404.
Even when there isn't a chain, it must be initialized to a empty X509
structure with sk_X509_new_null().
This patch fixes a segfault which appears with older versions of the SSL
libs (openssl 0.9.8, libressl 2.8.3...) because X509_chain_up_ref() does
not check the pointer.
This bug was introduced by b90d2cb ("MINOR: ssl: resolve issuers chain
later").
Should fix issue #516.
The goal is to use the ckch to store data from PEM files or <payload> and
only for that. This patch adresses the ckch->ocsp_issuer case. It finds
issuers chain if no chain is present in the ckch in ssl_sock_put_ckch_into_ctx(),
filling the ocsp_issuer from the chain must be done after.
It changes the way '.issuer' is managed: it tries to load '.issuer' in
ckch->ocsp_issuer first and then look for the issuer in the chain later
(in ssl_sock_load_ocsp() ). "ssl-load-extra-files" without the "issuer"
parameter can negate extra '.issuer' file check.
The goal is to use the ckch to store data from a loaded PEM file or a
<payload> and only for that. This patch addresses the ckch->chain case.
Looking for the issuers chain, if no chain is present in the ckch, can
be done in ssl_sock_put_ckch_into_ctx(). This way it is possible to know
the origin of the certificate chain without an extra state.
Move the cert_issuer_tree outside the global_ssl structure since it's
not a configuration variable. And move the declaration of the
issuer_chain structure in types/ssl_sock.h
Reorder the 'show ssl cert' output so it's easier to see if the whole
chain is correct.
For a chain to be correct, an "Issuer" line must have the same
content as the next "Subject" line.
Example:
Subject: /C=FR/ST=Paris/O=HAProxy Test Certificate/CN=test.haproxy.local
Issuer: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 2/CN=ca2.haproxy.local
Chain Subject: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 2/CN=ca2.haproxy.local
Chain Issuer: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 1/CN=ca1.haproxy.local
Chain Subject: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 1/CN=ca1.haproxy.local
Chain Issuer: /C=FR/ST=Paris/O=HAProxy Test Root CA/CN=root.haproxy.local
For each certificate in the chain, displays the issuer, so it's easy to
know if the chain is right.
Also rename "Chain" to "Chain Subject".
Example:
Chain Subject: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 2/CN=ca2.haproxy.local
Chain Issuer: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 1/CN=ca1.haproxy.local
Chain Subject: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 1/CN=ca1.haproxy.local
Chain Issuer: /C=FR/ST=Paris/O=HAProxy Test Root CA/CN=root.haproxy.local
Display the subject of each certificate contained in the chain in the
output of "show ssl cert <filename>".
Each subjects are on a unique line prefixed by "Chain: "
Example:
Chain: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 2/CN=ca2.haproxy.local
Chain: /C=FR/ST=Paris/O=HAProxy Test Intermediate CA 1/CN=ca1.haproxy.local
Sample fetch functions ssl_x_sha1(), ssl_fc_npn(), ssl_fc_alpn(),
ssl_fc_session_id(), as well as the CLI's "show cert details" handler
used to dereference the output buffer's <data> field by casting it to
"unsigned *". But while doing this could work before 1.9, it broke
starting with commit 843b7cbe9d ("MEDIUM: chunks: make the chunk struct's
fields match the buffer struct") which merged chunks and buffers, causing
the <data> field to become a size_t. The impact is only on 64-bit platform
and depends on the endianness: on little endian, there should never be any
non-zero bits in the field as it is supposed to have been zeroed before the
call, so it shouldbe harmless; on big endian, the high part of the value
only is written instead of the lower one, often making the result appear
4 billion times larger, and making such values dropped everywhere due to
being larger than a buffer.
It seems that it would be wise to try to re-enable strict-aliasing to
catch such errors.
This must be backported till 1.9.
