Commit 6a024330 authored by Dan Carpenter's avatar Dan Carpenter Committed by Linus Torvalds

drivers/virt/fsl_hypervisor.c: prevent integer overflow in ioctl

The "param.count" value is a u64 thatcomes from the user.  The code
later in the function assumes that param.count is at least one and if
it's not then it leads to an Oops when we dereference the ZERO_SIZE_PTR.

Also the addition can have an integer overflow which would lead us to
allocate a smaller "pages" array than required.  I can't immediately
tell what the possible run times implications are, but it's safest to
prevent the overflow.

Link: http://lkml.kernel.org/r/20181218082129.GE32567@kadam
Fixes: 6db71994 ("drivers/virt: introduce Freescale hypervisor management driver")
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Timur Tabi <timur@freescale.com>
Cc: Mihai Caraman <mihai.caraman@freescale.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8ea3663
...@@ -215,6 +215,9 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p) ...@@ -215,6 +215,9 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
* hypervisor. * hypervisor.
*/ */
lb_offset = param.local_vaddr & (PAGE_SIZE - 1); lb_offset = param.local_vaddr & (PAGE_SIZE - 1);
if (param.count == 0 ||
param.count > U64_MAX - lb_offset - PAGE_SIZE + 1)
return -EINVAL;
num_pages = (param.count + lb_offset + PAGE_SIZE - 1) >> PAGE_SHIFT; num_pages = (param.count + lb_offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
/* Allocate the buffers we need */ /* Allocate the buffers we need */
......
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