From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Fri, 29 Jun 2018 13:28:07 -0500
Subject: atm: zatm: Fix potential Spectre v1
Git-commit: ced9e191501e52b95e1b57b8e0db00943869eed0
Patch-mainline: v4.18-rc4
References: networking-stable-18_07_19
pool can be indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/atm/zatm.c:1491 zatm_ioctl() warn: potential spectre issue
'zatm_dev->pool_info' (local cap)
Fix this by sanitizing pool before using it to index
zatm_dev->pool_info
Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/atm/zatm.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/atm/zatm.c b/drivers/atm/zatm.c
index a8d2eb0ceb8d..2c288d1f42bb 100644
--- a/drivers/atm/zatm.c
+++ b/drivers/atm/zatm.c
@@ -1483,6 +1483,8 @@ static int zatm_ioctl(struct atm_dev *dev,unsigned int cmd,void __user *arg)
return -EFAULT;
if (pool < 0 || pool > ZATM_LAST_POOL)
return -EINVAL;
+ pool = array_index_nospec(pool,
+ ZATM_LAST_POOL + 1);
if (copy_from_user(&info,
&((struct zatm_pool_req __user *) arg)->info,
sizeof(info))) return -EFAULT;
--
2.18.0