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package/upx: fix CVE-2021-20285

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A flaw was found in upx canPack in p_lx_elf.cpp in UPX 3.96. This flaw
allows attackers to cause a denial of service (SEGV or buffer overflow
and application crash) or possibly have unspecified other impacts via a
crafted ELF. The highest threat from this vulnerability is to system
availability.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
This commit is contained in:
Fabrice Fontaine 2021-03-31 23:32:47 +02:00 committed by Peter Korsgaard
parent ce978e0a67
commit 92a6db4fc6
2 changed files with 83 additions and 0 deletions
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80
package/upx/0001-Check-DT_REL-DT_RELA-DT_RELSZ-DT_RELASZ.patch Normal file
View File

@ -0,0 +1,80 @@
From 3781df9da23840e596d5e9e8493f22666802fe6c Mon Sep 17 00:00:00 2001
From: John Reiser <jreiser@BitWagon.com>
Date: Fri, 11 Dec 2020 13:38:18 -0800
Subject: [PATCH] Check DT_REL/DT_RELA, DT_RELSZ/DT_RELASZ
https://github.com/upx/upx/issues/421
modified: p_lx_elf.cpp
[Retrieved from:
https://github.com/upx/upx/commit/3781df9da23840e596d5e9e8493f22666802fe6c]
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
---
src/p_lx_elf.cpp | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)
diff --git a/src/p_lx_elf.cpp b/src/p_lx_elf.cpp
index 182db192f..3a4101cf7 100644
--- a/src/p_lx_elf.cpp
+++ b/src/p_lx_elf.cpp
@@ -2222,8 +2222,20 @@ bool PackLinuxElf32::canPack()
int z_rsz = dt_table[Elf32_Dyn::DT_RELSZ];
if (z_rel && z_rsz) {
unsigned rel_off = get_te32(&dynseg[-1+ z_rel].d_val);
+ if ((unsigned)file_size <= rel_off) {
+ char msg[70]; snprintf(msg, sizeof(msg),
+ "bad Elf32_Dynamic[DT_REL] %#x\n",
+ rel_off);
+ throwCantPack(msg);
+ }
Elf32_Rel *rp = (Elf32_Rel *)&file_image[rel_off];
unsigned relsz = get_te32(&dynseg[-1+ z_rsz].d_val);
+ if ((unsigned)file_size <= relsz) {
+ char msg[70]; snprintf(msg, sizeof(msg),
+ "bad Elf32_Dynamic[DT_RELSZ] %#x\n",
+ relsz);
+ throwCantPack(msg);
+ }
Elf32_Rel *last = (Elf32_Rel *)(relsz + (char *)rp);
for (; rp < last; ++rp) {
unsigned r_va = get_te32(&rp->r_offset);
@@ -2562,14 +2574,26 @@ PackLinuxElf64::canPack()
int z_rel = dt_table[Elf64_Dyn::DT_RELA];
int z_rsz = dt_table[Elf64_Dyn::DT_RELASZ];
if (z_rel && z_rsz) {
- unsigned rel_off = get_te64(&dynseg[-1+ z_rel].d_val);
+ upx_uint64_t rel_off = get_te64(&dynseg[-1+ z_rel].d_val);
+ if ((u64_t)file_size <= rel_off) {
+ char msg[70]; snprintf(msg, sizeof(msg),
+ "bad Elf64_Dynamic[DT_RELA] %#llx\n",
+ rel_off);
+ throwCantPack(msg);
+ }
Elf64_Rela *rp = (Elf64_Rela *)&file_image[rel_off];
- unsigned relsz = get_te64(&dynseg[-1+ z_rsz].d_val);
+ upx_uint64_t relsz = get_te64(&dynseg[-1+ z_rsz].d_val);
+ if ((u64_t)file_size <= relsz) {
+ char msg[70]; snprintf(msg, sizeof(msg),
+ "bad Elf64_Dynamic[DT_RELASZ] %#llx\n",
+ relsz);
+ throwCantPack(msg);
+ }
Elf64_Rela *last = (Elf64_Rela *)(relsz + (char *)rp);
for (; rp < last; ++rp) {
- unsigned r_va = get_te64(&rp->r_offset);
+ upx_uint64_t r_va = get_te64(&rp->r_offset);
if (r_va == user_init_ava) { // found the Elf64_Rela
- unsigned r_info = get_te64(&rp->r_info);
+ upx_uint64_t r_info = get_te64(&rp->r_info);
unsigned r_type = ELF64_R_TYPE(r_info);
if (Elf64_Ehdr::EM_AARCH64 == e_machine
&& R_AARCH64_RELATIVE == r_type) {
@@ -2581,7 +2605,7 @@ PackLinuxElf64::canPack()
}
else {
char msg[50]; snprintf(msg, sizeof(msg),
- "bad relocation %#x DT_INIT_ARRAY[0]",
+ "bad relocation %#llx DT_INIT_ARRAY[0]",
r_info);
throwCantPack(msg);
}

3
package/upx/upx.mk
View File

@ -11,6 +11,9 @@ UPX_LICENSE = GPL-2.0+
UPX_LICENSE_FILES = COPYING
UPX_CPE_ID_VENDOR = upx_project
# 0001-Check-DT_REL-DT_RELA-DT_RELSZ-DT_RELASZ.patch
UPX_IGNORE_CVES += CVE-2021-20285
HOST_UPX_DEPENDENCIES = host-ucl host-zlib
# We need to specify all, otherwise the default target only prints a message