Bad header can have large length field which can cause OOB.
cptr is the last bytes for read, and the eeprom is parsed
from high to low address. The OOB, triggered by the condition
length > cptr could cause memory error with a read on
negative index.
There are some sanity check around length, but it is not
compared with cptr (the remaining bytes). Here, the
corrupted/bad EEPROM can cause panic.
I was able to reproduce the crash, but I cannot find the
log and the reproducer now. After I applied the patch, the
bug is no longer reproducible.
Signed-off-by: Zekun Shen <[email protected]>
---
drivers/net/wireless/ath/ath9k/ar9003_eeprom.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c b/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c
index b4885a700296..b0a4ca3559fd 100644
--- a/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c
+++ b/drivers/net/wireless/ath/ath9k/ar9003_eeprom.c
@@ -3351,7 +3351,8 @@ static int ar9300_eeprom_restore_internal(struct ath_hw *ah,
"Found block at %x: code=%d ref=%d length=%d major=%d minor=%d\n",
cptr, code, reference, length, major, minor);
if ((!AR_SREV_9485(ah) && length >= 1024) ||
- (AR_SREV_9485(ah) && length > EEPROM_DATA_LEN_9485)) {
+ (AR_SREV_9485(ah) && length > EEPROM_DATA_LEN_9485) ||
+ (length > cptr)) {
ath_dbg(common, EEPROM, "Skipping bad header\n");
cptr -= COMP_HDR_LEN;
continue;
--
2.23.0.rc1
Zekun Shen <[email protected]> wrote:
> Bad header can have large length field which can cause OOB.
> cptr is the last bytes for read, and the eeprom is parsed
> from high to low address. The OOB, triggered by the condition
> length > cptr could cause memory error with a read on
> negative index.
>
> There are some sanity check around length, but it is not
> compared with cptr (the remaining bytes). Here, the
> corrupted/bad EEPROM can cause panic.
>
> I was able to reproduce the crash, but I cannot find the
> log and the reproducer now. After I applied the patch, the
> bug is no longer reproducible.
>
> Signed-off-by: Zekun Shen <[email protected]>
> Signed-off-by: Kalle Valo <[email protected]>
Patch applied to ath-next branch of ath.git, thanks.
23151b9ae79e ath9k: fix OOB read ar9300_eeprom_restore_internal
--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches