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From 480b6fa3662ba8ffeee274bf0d37423413c01e55 Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Wed, 3 Mar 2021 21:40:53 +0100
Subject: [PATCH] readelf: Sanity check verneed and verdef offsets in handle_symtab.
We are going through vna_next, vn_next and vd_next in a while loop.
Make sure that all offsets are sane. We don't want things to wrap
around so we go in cycles.
https://sourceware.org/bugzilla/show_bug.cgi?id=27501
Signed-off-by: Mark Wielaard <mark@klomp.org>
Upstream-Status: Backport [https://sourceware.org/git/?p=elfutils.git;a=commit;h=480b6fa3662ba8ffeee274bf0d37423413c01e55]
CVE: CVE-2021-33294
Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
---
src/ChangeLog | 5 +++++
src/readelf.c | 10 +++++++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/src/ChangeLog b/src/ChangeLog
index 6af977e..f0d9e39 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2021-03-03 Mark Wielaard <mark@klomp.org>
+
+ * readelf.c (handle_symtab): Sanity check verneed vna_next,
+ vn_next and verdef vd_next offsets.
+
2019-11-26 Mark Wielaard <mark@klomp.org>
* Makefile.am (BUILD_STATIC): Add libraries needed for libdw.
diff --git a/src/readelf.c b/src/readelf.c
index 5994615..ab7a1c1 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -2550,7 +2550,9 @@ handle_symtab (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr)
&vernaux_mem);
while (vernaux != NULL
&& vernaux->vna_other != *versym
- && vernaux->vna_next != 0)
+ && vernaux->vna_next != 0
+ && (verneed_data->d_size - vna_offset
+ >= vernaux->vna_next))
{
/* Update the offset. */
vna_offset += vernaux->vna_next;
@@ -2567,6 +2569,9 @@ handle_symtab (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr)
/* Found it. */
break;
+ if (verneed_data->d_size - vn_offset < verneed->vn_next)
+ break;
+
vn_offset += verneed->vn_next;
verneed = (verneed->vn_next == 0
? NULL
@@ -2602,6 +2607,9 @@ handle_symtab (Ebl *ebl, Elf_Scn *scn, GElf_Shdr *shdr)
/* Found the definition. */
break;
+ if (verdef_data->d_size - vd_offset < verdef->vd_next)
+ break;
+
vd_offset += verdef->vd_next;
verdef = (verdef->vd_next == 0
? NULL
--
2.25.1
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