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From: "Gustavo A. R. Silva" <>
To: Chas Williams <>,
	"David S. Miller" <>
	"Gustavo A. R. Silva" <>
Subject: [PATCH] atm: zatm: Fix potential Spectre v1
Date: Fri, 29 Jun 2018 13:28:07 -0500	[thread overview]
Message-ID: <> (raw)

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

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].


Signed-off-by: Gustavo A. R. Silva <>
 drivers/atm/zatm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/atm/zatm.c b/drivers/atm/zatm.c
index a8d2eb0..2c288d1 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;

             reply	other threads:[~2018-06-29 18:52 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-29 18:28 Gustavo A. R. Silva [this message]
2018-06-30 12:25 ` David Miller
  -- strict thread matches above, loose matches on Subject: below --
2018-05-03 18:17 Gustavo A. R. Silva
2018-05-03 19:09 ` Randy Dunlap
2018-05-03 19:25   ` David Miller
2018-05-04 16:54 ` David Miller

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