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BUG/MEDIUM: checks: Fix off-by-one in allocation of SMTP greeting cmd

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The allocation did not account for either the trailing null byte or the
space, leading to a buffer overwrite.

This bug was detected by an assertion failure in the allocator. But can
also be easily detected using valgrind:

    ==25827== Invalid write of size 1
    ==25827==    at 0x6529759: __vsprintf_chk (vsprintf_chk.c:84)
    ==25827==    by 0x65296AC: __sprintf_chk (sprintf_chk.c:31)
    ==25827==    by 0x4D6AB7: sprintf (stdio2.h:33)
    ==25827==    by 0x4D6AB7: proxy_parse_smtpchk_opt (check.c:1799)
    ==25827==    by 0x4A7DDD: cfg_parse_listen (cfgparse-listen.c:2269)
    ==25827==    by 0x494AD3: readcfgfile (cfgparse.c:2167)
    ==25827==    by 0x542995: init (haproxy.c:2021)
    ==25827==    by 0x421DD2: main (haproxy.c:3121)
    ==25827==  Address 0x78712a8 is 0 bytes after a block of size 24 alloc'd
    ==25827==    at 0x4C2FB55: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==25827==    by 0x4D6A8C: proxy_parse_smtpchk_opt (check.c:1797)
    ==25827==    by 0x4A7DDD: cfg_parse_listen (cfgparse-listen.c:2269)
    ==25827==    by 0x494AD3: readcfgfile (cfgparse.c:2167)
    ==25827==    by 0x542995: init (haproxy.c:2021)
    ==25827==    by 0x421DD2: main (haproxy.c:3121)

This patch fixes issue #681.

This bug was introduced in commit fbcc77c6baa7edee85be9c2384d12c55ef651a5a,
which first appeared in 2.2-dev7. No backport needed.
This commit is contained in:
Tim Duesterhus 2020-06-12 15:58:48 +02:00 committed by Willy Tarreau
parent f28d5c9ac6
commit 2867b402ac
1 changed files with 2 additions and 1 deletions
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3
src/check.c
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@ -1794,7 +1794,8 @@ int proxy_parse_smtpchk_opt(char **args, int cur_arg, struct proxy *curpx, struc
cur_arg += 2; cur_arg += 2;
if (*args[cur_arg] && *args[cur_arg+1] && if (*args[cur_arg] && *args[cur_arg+1] &&
(strcmp(args[cur_arg], "EHLO") == 0 || strcmp(args[cur_arg], "HELO") == 0)) { (strcmp(args[cur_arg], "EHLO") == 0 || strcmp(args[cur_arg], "HELO") == 0)) {
cmd = calloc(strlen(args[cur_arg]) + strlen(args[cur_arg+1]) + 1, sizeof(*cmd)); /* <EHLO|HELO> + space (1) + <host> + null byte (1) */
cmd = calloc(strlen(args[cur_arg]) + 1 + strlen(args[cur_arg+1]) + 1, sizeof(*cmd));
if (cmd) if (cmd)
sprintf(cmd, "%s %s", args[cur_arg], args[cur_arg+1]); sprintf(cmd, "%s %s", args[cur_arg], args[cur_arg+1]);
} }