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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: 6db7199407 ("drivers/virt: introduce Freescale hypervisor management driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Andrew 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Carpenter 2019-05-14 15:47:03 -07:00 committed by Linus Torvalds
parent c8ea3663f7
commit 6a02433065
1 changed files with 3 additions and 0 deletions
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3
drivers/virt/fsl_hypervisor.c
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@ -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 */