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* [PATCH] atm: zatm: Fix potential Spectre v1
@ 2018-05-03 18:17 Gustavo A. R. Silva
  2018-05-03 19:09 ` Randy Dunlap
  2018-05-04 16:54 ` David Miller
  0 siblings, 2 replies; 6+ messages in thread
From: Gustavo A. R. Silva @ 2018-05-03 18:17 UTC (permalink / raw)
  To: Chas Williams, David S. Miller
  Cc: linux-atm-general, netdev, linux-kernel, Gustavo A. R. Silva

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:1462 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

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/atm/zatm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/atm/zatm.c b/drivers/atm/zatm.c
index 1ef67db..9c9a229 100644
--- a/drivers/atm/zatm.c
+++ b/drivers/atm/zatm.c
@@ -28,6 +28,7 @@
 #include <asm/io.h>
 #include <linux/atomic.h>
 #include <linux/uaccess.h>
+#include <linux/nospec.h>
 
 #include "uPD98401.h"
 #include "uPD98402.h"
@@ -1458,6 +1459,8 @@ 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);
 				spin_lock_irqsave(&zatm_dev->lock, flags);
 				info = zatm_dev->pool_info[pool];
 				if (cmd == ZATM_GETPOOLZ) {
-- 
2.7.4

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] atm: zatm: Fix potential Spectre v1
@ 2018-06-29 18:28 Gustavo A. R. Silva
  2018-06-30 12:25 ` David Miller
  0 siblings, 1 reply; 6+ messages in thread
From: Gustavo A. R. Silva @ 2018-06-29 18:28 UTC (permalink / raw)
  To: Chas Williams, David S. Miller
  Cc: linux-atm-general, netdev, linux-kernel, Gustavo A. R. Silva

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

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 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;
-- 
2.7.4


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2018-06-30 12:25 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-05-03 18:17 [PATCH] atm: zatm: Fix potential Spectre v1 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
2018-06-29 18:28 Gustavo A. R. Silva
2018-06-30 12:25 ` David Miller

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