From 6a1cf708dd5681b517744d6d4fac02e4e4a0aa2e Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Wed, 11 Mar 2015 21:03:50 -0400 Subject: [PATCH] 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. --- ChangeLog | 6 ++++++ NEWS | 2 +- elf/cache.c | 4 +++- 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/ChangeLog b/ChangeLog index 7360079..f12516b 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2015-03-11 Aurelien Jarno + + [BZ #18093] + * elf/cache.c (load_aux_cache): Regenerate the cache if it has + the wrong size. + 2015-03-11 Paul Pluzhnikov [BZ #18043] diff --git a/NEWS b/NEWS index 1cee779..6568085 100644 --- a/NEWS +++ b/NEWS @@ -14,7 +14,7 @@ Version 2.22 17792, 17836, 17912, 17916, 17932, 17944, 17949, 17964, 17965, 17967, 17969, 17978, 17987, 17991, 17996, 17998, 17999, 18019, 18020, 18029, 18030, 18032, 18036, 18038, 18039, 18042, 18043, 18046, 18047, 18068, - 18104, 18110, 18111. + 18093, 18104, 18110, 18111. * Character encoding and ctype tables were updated to Unicode 7.0.0, using new generator scripts contributed by Pravin Satpute and Mike FABIAN (Red diff --git a/elf/cache.c b/elf/cache.c index 1732268..bde7984 100644 --- a/elf/cache.c +++ b/elf/cache.c @@ -698,7 +698,9 @@ load_aux_cache (const char *aux_cache_name) if (aux_cache == MAP_FAILED || aux_cache_size < sizeof (struct aux_cache_file) || memcmp (aux_cache->magic, AUX_CACHEMAGIC, sizeof AUX_CACHEMAGIC - 1) - || aux_cache->nlibs >= aux_cache_size) + || aux_cache_size != (sizeof(struct aux_cache_file) + + aux_cache->nlibs * sizeof(struct aux_cache_file_entry) + + aux_cache->len_strings)) { close (fd); init_aux_cache (); -- 2.7.4