From 45a0eaf77022963d639d6d19871dbab7b79703fc Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Tue, 23 Oct 2018 19:02:06 +1030 Subject: [PATCH] PR23806, NULL pointer dereference in merge_strings PR 23806 * merge.c (_bfd_add_merge_section): Don't attempt to merge sections with ridiculously large alignments. Upstream-Status: Backport CVE: CVE-2018-18606 Signed-off-by: Zhixiong Chi --- bfd/ChangeLog | 6 ++++++ bfd/merge.c | 15 +++++++++++---- 2 files changed, 17 insertions(+), 4 deletions(-) --- a/bfd/merge.c +++ b/bfd/merge.c @@ -24,6 +24,7 @@ as used in ELF SHF_MERGE. */ #include "sysdep.h" +#include #include "bfd.h" #include "elf-bfd.h" #include "libbfd.h" @@ -385,12 +386,18 @@ _bfd_add_merge_section (bfd *abfd, void return TRUE; } - align = sec->alignment_power; - if ((sec->entsize < (unsigned) 1 << align +#ifndef CHAR_BIT +#define CHAR_BIT 8 +#endif + if (sec->alignment_power >= sizeof (align) * CHAR_BIT) + return TRUE; + + align = 1u << sec->alignment_power; + if ((sec->entsize < align && ((sec->entsize & (sec->entsize - 1)) || !(sec->flags & SEC_STRINGS))) - || (sec->entsize > (unsigned) 1 << align - && (sec->entsize & (((unsigned) 1 << align) - 1)))) + || (sec->entsize > align + && (sec->entsize & (align - 1)))) { /* Sanity check. If string character size is smaller than alignment, then we require character size to be a power