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Message-Id: <20180720121340.598723513@linuxfoundation.org>
Date: Fri, 20 Jul 2018 14:13:42 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 12/31] atm: zatm: Fix potential Spectre v1
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
[ Upstream commit ced9e191501e52b95e1b57b8e0db00943869eed0 ]
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@...eddedor.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/atm/zatm.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/atm/zatm.c
+++ b/drivers/atm/zatm.c
@@ -1481,6 +1481,8 @@ static int zatm_ioctl(struct atm_dev *de
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;
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