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dm ioctl: prevent potential spectre v1 gadget

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[ Upstream commit cd9c88da17 ]

It appears like cmd could be a Spectre v1 gadget as it's supplied by a
user and used as an array index. Prevent the contents of kernel memory
from being leaked to userspace via speculative execution by using
array_index_nospec.

Signed-off-by: Jordy Zomer <jordy@pwning.systems>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jordy Zomer 2022-01-29 15:58:39 +01:00 committed by Greg Kroah-Hartman
parent 09c358d8ae
commit dd86064417
1 changed files with 2 additions and 0 deletions
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2
drivers/md/dm-ioctl.c
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@ -18,6 +18,7 @@
#include <linux/dm-ioctl.h>
#include <linux/hdreg.h>
#include <linux/compat.h>
#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <linux/ima.h>
@ -1788,6 +1789,7 @@ static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
return NULL;
cmd = array_index_nospec(cmd, ARRAY_SIZE(_ioctls));
*ioctl_flags = _ioctls[cmd].flags;
return _ioctls[cmd].fn;
}