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mm/gup: do not return 0 from pin_user_pages_fast() for bad args 

These routines are not intended to return zero, the callers cannot do
anything sane with a 0 return.  They should return an error which means
future calls to GUP will not succeed, or they should return some non-zero
number of pinned pages which means GUP should be called again.

If start + nr_pages overflows it should return -EOVERFLOW to signal the
arguments are invalid.

Syzkaller keeps tripping on this when fuzzing GUP arguments.

Link: https://lkml.kernel.org/r/0-v1-3d5ed1f20d50+104-gup_overflow_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reported-by: syzbot+353c7be4964c6253f24a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000094fdd05faa4d3a4@google.com
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jason Gunthorpe 2023-06-19 15:27:25 -03:00 committed by Andrew Morton
parent 0b52c42035
commit 9883c7f840
1 changed files with 1 additions and 1 deletions
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2
mm/gup.c
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@ -3080,7 +3080,7 @@ static int internal_get_user_pages_fast(unsigned long start,
start = untagged_addr(start) & PAGE_MASK;
len = nr_pages << PAGE_SHIFT;
if (check_add_overflow(start, len, &end))
return 0;
return -EOVERFLOW;
if (end > TASK_SIZE_MAX)
return -EFAULT;
if (unlikely(!access_ok((void __user *)start, len)))