Red Hat Bugzilla – Bug 1325138
glibc: Corrupted aux-cache causes ldconfig to segfault
Last modified: 2017-08-01 14:06:55 EDT
+++ This bug was initially created as a clone of Bug #1325135 +++ Description of problem: ldconfig segfaults if the /var/cache/ldconfig/aux-cache is corrupted. Version-Release number of selected component (if applicable): Red Hat Enterprise Linux 6 glibc-2.12-1.166.el6_7.7.x86_64 How reproducible: Always Steps to Reproduce: 1. Remove some entries from /var/cache/ldconfig/aux-cache to make corrupt file. 2. Run ldconfig to rebuild cache 3. Actual results: # ldconfig Segmentation fault (core dumped) Expected results: ldconfig should check for corrupt cache and rebuild it again. Additional info: https://sourceware.org/bugzilla/show_bug.cgi?id=18093
The upstream patch is incomplete because it does not perform an fsync before the rename, and some file systems need that.
We need to fix the fsync issue and backport this patch. I'm setting devel_cond_nak+ upstream/capacity for this since we need a fix upstream before this is complete, but leaving flags Patch because we could backport the existing fix and move incrementally in the right direction (towards upstream solution). commit 6a1cf708dd5681b517744d6d4fac02e4e4a0aa2e Author: Aurelien Jarno <aurelien@aurel32.net> Date: Wed Mar 11 21:03:50 2015 -0400 Fix ldconfig segmentation fault with corrupted cache (Bug 18093). ldconfig is using an aux-cache to speed up the ld.so.cache update. It is read by mmaping the file to a structure which contains data offsets used as pointers. As they are not checked, it is not hard to get ldconfig to segfault with a corrupted file. This happens for instance if the file is truncated, which is common following a filesystem check following a system crash. This can be reproduced for example by truncating the file to roughly half of it's size. There is already some code in elf/cache.c (load_aux_cache) to check for a corrupted aux cache, but it happens to be broken and not enough. The test (aux_cache->nlibs >= aux_cache_size) compares the number of libs entry with the cache size. It's a non sense, as it basically assumes that each library entry is a 1 byte... Instead this commit computes the theoretical cache size using the headers and compares it to the real size.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2017:1916