[Bug general/23542] heap-buffer-overflow in /elfutils/src/elflint.c:2055 check_sysv_hash

mark at klomp dot org sourceware-bugzilla@sourceware.org
Fri Aug 17 20:19:00 GMT 2018


Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
                 CC|                            |mark at klomp dot org

--- Comment #1 from Mark Wielaard <mark at klomp dot org> ---
Replicated under valgrind:

==12265== Conditional jump or move depends on uninitialised value(s)
==12265==    at 0x1111E9: check_sysv_hash (elflint.c:2056)
==12265==    by 0x1111E9: check_hash.isra.14 (elflint.c:2356)
==12265==    by 0x117B80: check_sections (elflint.c:4162)
==12265==    by 0x119364: process_elf_file (elflint.c:4740)
==12265==    by 0x119364: process_file (elflint.c:242)
==12265==    by 0x10C57C: main (elflint.c:175)

The issue is that the sanity check at the start of the function overflows
because it does 32bit unsigned arithmetic. Changing it to do unsigned long long
arithmetic makes the check catch the issue:

diff --git a/src/elflint.c b/src/elflint.c
index eec799b2..9d49c47f 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -2023,7 +2023,7 @@ check_sysv_hash (Ebl *ebl, GElf_Shdr *shdr, Elf_Data
*data, int idx,
   Elf32_Word nbucket = ((Elf32_Word *) data->d_buf)[0];
   Elf32_Word nchain = ((Elf32_Word *) data->d_buf)[1];

-  if (shdr->sh_size < (2 + nbucket + nchain) * sizeof (Elf32_Word))
+  if (shdr->sh_size  < (2ULL + nbucket + nchain) * sizeof (Elf32_Word))
       ERROR (gettext ("\
 section [%2d] '%s': hash table section is too small (is %ld, expected

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