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[PATCH 01/17] libelf: Fix possible unbounded stack usage in elf_getarsym.
- From: Mark Wielaard <mjw at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Sat, 23 May 2015 23:10:14 +0200
- Subject: [PATCH 01/17] libelf: Fix possible unbounded stack usage in elf_getarsym.
The number of entries in the index can be large, don't use alloca to
read in temporary data, use malloc (and free after out).
Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
libelf/ChangeLog | 5 +++++
libelf/elf_getarsym.c | 14 ++++++++++++--
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index ed2ddd8..17ab740 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,8 @@
+2015-05-16 Mark Wielaard <mjw@redhat.com>
+
+ * elf_getarsym.c (elf_getarsym): Allocate temporary file_date with
+ malloc, not alloca. Call free after out.
+
2015-05-14 Mark Wielaard <mjw@redhat.com>
* elf_update.c (write_file): Use posix_fallocate instead of
diff --git a/libelf/elf_getarsym.c b/libelf/elf_getarsym.c
index 40633aa..fa9cd42 100644
--- a/libelf/elf_getarsym.c
+++ b/libelf/elf_getarsym.c
@@ -1,5 +1,5 @@
/* Return symbol table of archive.
- Copyright (C) 1998-2000, 2002, 2005, 2009, 2012, 2014 Red Hat, Inc.
+ Copyright (C) 1998-2000, 2002, 2005, 2009, 2012, 2014, 2015 Red Hat, Inc.
This file is part of elfutils.
Written by Ulrich Drepper <drepper@redhat.com>, 1998.
@@ -106,6 +106,9 @@ elf_getarsym (elf, ptr)
/* In case we find no index remember this for the next call. */
elf->state.ar.ar_sym = (Elf_Arsym *) -1l;
+ /* We might have to allocate some temporary data for reading. */
+ void *temp_data = NULL;
+
struct ar_hdr *index_hdr;
if (elf->map_address == NULL)
{
@@ -210,7 +213,13 @@ elf_getarsym (elf, ptr)
if (elf->map_address == NULL)
{
- file_data = alloca (sz);
+ temp_data = malloc (sz);
+ if (temp_data == NULL)
+ {
+ __libelf_seterrno (ELF_E_NOMEM);
+ goto out;
+ }
+ file_data = temp_data;
ar_sym_len += index_size - n * w;
Elf_Arsym *newp = (Elf_Arsym *) realloc (elf->state.ar.ar_sym,
@@ -299,6 +308,7 @@ elf_getarsym (elf, ptr)
result = elf->state.ar.ar_sym;
out:
+ free (temp_data);
rwlock_unlock (elf->lock);
}
--
1.8.3.1