In the unlikely situation that elf_strptr was called on a section with
sh_size already set, but that doesn't have any data yet we could crash
trying to verify the string to return.
This could happen for example when a new section was created with
elf_newscn, but no data having been added yet.
* libelf/elf_strptr.c (elf_strptr): Check strscn->rawdata_base
is not NULL.
https://sourceware.org/bugzilla/show_bug.cgi?id=32672
Signed-off-by: Mark Wielaard <m...@klomp.org>
---
libelf/elf_strptr.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/libelf/elf_strptr.c b/libelf/elf_strptr.c
index c5a94f82aa55..7be7f5e8fb18 100644
--- a/libelf/elf_strptr.c
+++ b/libelf/elf_strptr.c
@@ -1,5 +1,6 @@
/* Return string pointer from string section.
Copyright (C) 1998-2002, 2004, 2008, 2009, 2015 Red Hat, Inc.
+ Copyright (C) 2025 Mark J. Wielaard <m...@klomp.org>
This file is part of elfutils.
Contributed by Ulrich Drepper <drep...@redhat.com>, 1998.
@@ -183,9 +184,12 @@ elf_strptr (Elf *elf, size_t idx, size_t offset)
// initialized yet (when data_read is zero). So we cannot just
// look at the rawdata.d.d_size.
- /* Make sure the string is NUL terminated. Start from the end,
- which very likely is a NUL char. */
- if (likely (validate_str (strscn->rawdata_base, offset, sh_size)))
+ /* First check there actually is any data. This could be a new
+ section which hasn't had any data set yet. Then make sure
+ the string is at a valid offset and NUL terminated. */
+ if (unlikely (strscn->rawdata_base == NULL))
+ __libelf_seterrno (ELF_E_INVALID_SECTION);
+ else if (likely (validate_str (strscn->rawdata_base, offset, sh_size)))
result = &strscn->rawdata_base[offset];
else
__libelf_seterrno (ELF_E_INVALID_INDEX);
--
2.48.1
