File 0064-fw_cfg-add-check-to-validate-curren.patch of Package qemu-linux-user.openSUSE_Leap_42.1_Update
From 844be8c0846f6d0e5d653050a979905b92aa7b68 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Tue, 5 Jan 2016 23:17:00 -0700
Subject: [PATCH] fw_cfg: add check to validate current entry value
When processing firmware configurations, an OOB r/w access occurs
if 's->cur_entry' is set to be invalid(FW_CFG_INVALID=0xffff).
Add a check to validate 's->cur_entry' to avoid such access.
Reported-by: Donghai Zdh <donghai.zdh@alibaba-inc.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
[BR: BSC#961691 CVE-2016-1714]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
hw/nvram/fw_cfg.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 68eff77..e73c0fb 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -233,12 +233,15 @@ static void fw_cfg_reboot(FWCfgState *s)
static void fw_cfg_write(FWCfgState *s, uint8_t value)
{
int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
- FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
+ FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL :
+ &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
trace_fw_cfg_write(s, value);
- if (s->cur_entry & FW_CFG_WRITE_CHANNEL && e->callback &&
- s->cur_offset < e->len) {
+ if (s->cur_entry & FW_CFG_WRITE_CHANNEL
+ && e != NULL
+ && e->callback
+ && s->cur_offset < e->len) {
e->data[s->cur_offset++] = value;
if (s->cur_offset == e->len) {
e->callback(e->callback_opaque, e->data);
@@ -267,7 +270,8 @@ static int fw_cfg_select(FWCfgState *s, uint16_t key)
static uint8_t fw_cfg_read(FWCfgState *s)
{
int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
- FWCfgEntry *e = &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
+ FWCfgEntry *e = (s->cur_entry == FW_CFG_INVALID) ? NULL :
+ &s->entries[arch][s->cur_entry & FW_CFG_ENTRY_MASK];
uint8_t ret;
if (s->cur_entry == FW_CFG_INVALID || !e->data || s->cur_offset >= e->len)