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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
---
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 182db192..3a4101cf 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);
}
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