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| author | Dmitry V. Levin <ldv@altlinux.org> | 2015-06-18 21:40:46 +0000 |
|---|---|---|
| committer | Dmitry V. Levin <ldv@altlinux.org> | 2015-06-23 09:37:28 +0000 |
| commit | b57525f1a376149840f740a31535681c07152ba4 (patch) | |
| tree | c520a3234fda67b9c99562eb1b06e090e9cc2bb5 /resolv/res_hconf.c | |
| parent | 47852c972d1ad80d8b38d9e94507b27df0ede421 (diff) | |
| download | glibc-b57525f1a376149840f740a31535681c07152ba4.zip glibc-b57525f1a376149840f740a31535681c07152ba4.tar.gz glibc-b57525f1a376149840f740a31535681c07152ba4.tar.bz2 | |
Fix potential hanging of gethostbyaddr_r/gethostbyname_r
When "reorder" resolver option is enabled, threads of a multi-threaded process
could hang in gethostbyaddr_r, gethostbyname_r, or gethostbyname2_r.
Due to a trivial bug in _res_hconf_reorder_addrs, simultaneous
invocations of this function in a multi-threaded process could result to
_res_hconf_reorder_addrs returning without releasing the lock it holds,
causing other threads to block indefinitely while waiting for the lock
that is not going to be released.
[BZ #17977]
* resolv/res_hconf.c (_res_hconf_reorder_addrs): Fix unlocking
when initializing interface list, based on the bug analysis
and the patch proposed by Eric Newton.
* resolv/tst-res_hconf_reorder.c: New test.
* resolv/Makefile [$(have-thread-library) = yes] (tests): Add
tst-res_hconf_reorder.
($(objpfx)tst-res_hconf_reorder): Depend on $(libdl)
and $(shared-thread-library).
(tst-res_hconf_reorder-ENV): New variable.
Diffstat (limited to 'resolv/res_hconf.c')
| -rw-r--r-- | resolv/res_hconf.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/resolv/res_hconf.c b/resolv/res_hconf.c index c9642ce..0d4f3f4 100644 --- a/resolv/res_hconf.c +++ b/resolv/res_hconf.c @@ -473,10 +473,10 @@ _res_hconf_reorder_addrs (struct hostent *hp) errno = save; num_ifs = new_num_ifs; - - __libc_lock_unlock (lock); } + __libc_lock_unlock (lock); + __close (sd); } |