This is a note to let you know that I've just added the patch titled
mm/gup: do not return 0 from pin_user_pages_fast() for bad args
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-gup-do-not-return-0-from-pin_user_pages_fast-for-bad-args.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9883c7f84053cec2826ca3c56254601b5ce9cdbe Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
Date: Mon, 19 Jun 2023 15:27:25 -0300
Subject: mm/gup: do not return 0 from pin_user_pages_fast() for bad args
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
commit 9883c7f84053cec2826ca3c56254601b5ce9cdbe upstream.
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@xxxxxxxxxx
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reported-by: syzbot+353c7be4964c6253f24a@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/000000000000094fdd05faa4d3a4@xxxxxxxxxx
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Reviewed-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2977,7 +2977,7 @@ static int internal_get_user_pages_fast(
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)))
Patches currently in stable-queue which might be from jgg@xxxxxxxxxx are
queue-6.4/mm-gup-do-not-return-0-from-pin_user_pages_fast-for-bad-args.patch
