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CLEANUP: cache: use read_u32/write_u32 to access the cache entry's hash

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Enabling strict aliasing fails on the cache's hash which is a series of
20 bytes cast as u32. And in practice it could even fail on some archs
if the http_txn didn't guarantee the hash was properly aligned. Let's
use read_u32() to read the value and write_u32() to set it, this makes
sure the compiler emits the correct code to access these and knows about
the intentional aliasing.
This commit is contained in:
Willy Tarreau 2020-02-25 09:35:07 +01:00
parent 2b9f0664d6
commit 8b5075806d
2 changed files with 6 additions and 4 deletions
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7
src/cache.c
View File

@ -36,6 +36,7 @@
#include <common/hash.h>
#include <common/htx.h>
#include <common/initcall.h>
#include <common/net_helper.h>
#define CACHE_FLT_F_IMPLICIT_DECL 0x00000001 /* The cache filtre was implicitly declared (ie without
* the filter keyword) */
@ -95,7 +96,7 @@ struct cache_entry *entry_exist(struct cache *cache, char *hash)
struct eb32_node *node;
struct cache_entry *entry;
node = eb32_lookup(&cache->entries, (*(unsigned int *)hash));
node = eb32_lookup(&cache->entries, read_u32(hash));
if (!node)
return NULL;
@ -549,7 +550,7 @@ enum act_return http_action_store_cache(struct act_rule *rule, struct proxy *px,
struct shared_context *shctx = shctx_ptr(cconf->c.cache);
struct cache_st *cache_ctx = NULL;
struct cache_entry *object, *old;
unsigned int key = *(unsigned int *)txn->cache_hash;
unsigned int key = read_u32(txn->cache_hash);
struct htx *htx;
struct http_hdr_ctx ctx;
size_t hdrs_len = 0;
@ -1530,7 +1531,7 @@ static int cli_io_handler_show_cache(struct appctx *appctx)
}
entry = container_of(node, struct cache_entry, eb);
chunk_printf(&trash, "%p hash:%u size:%u (%u blocks), refcount:%u, expire:%d\n", entry, (*(unsigned int *)entry->hash), block_ptr(entry)->len, block_ptr(entry)->block_count, block_ptr(entry)->refcount, entry->expire - (int)now.tv_sec);
chunk_printf(&trash, "%p hash:%u size:%u (%u blocks), refcount:%u, expire:%d\n", entry, read_u32(entry->hash), block_ptr(entry)->len, block_ptr(entry)->block_count, block_ptr(entry)->refcount, entry->expire - (int)now.tv_sec);
next_key = node->key + 1;
appctx->ctx.cli.i0 = next_key;

3
src/http_ana.c
View File

@ -14,6 +14,7 @@
#include <common/config.h>
#include <common/debug.h>
#include <common/htx.h>
#include <common/net_helper.h>
#include <common/uri_auth.h>
#include <types/capture.h>
@ -5047,7 +5048,7 @@ void http_init_txn(struct stream *s)
: 0);
txn->status = -1;
txn->errmsg = NULL;
*(unsigned int *)txn->cache_hash = 0;
write_u32(txn->cache_hash, 0);
txn->cookie_first_date = 0;
txn->cookie_last_date = 0;