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Commit ced9e191 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by David S. Miller
Browse files

atm: zatm: Fix potential Spectre v1 

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: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c7f653e0

drivers/atm/zatm.c

+2 −0
Original line number Diff line number Diff line
@@ -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;