6.16-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit 33503c083fda048c77903460ac0429e1e2c0e341 upstream.
If the allocated size exceeds UINT_MAX, then it's necessary to cast the mr->nr_pages value to size_t to prevent it from overflowing. In practice this isn't much of a concern as the required memory size will have been validated upfront, and accounted to the user. And > 4GB sizes will be necessary to make the lack of a cast a problem, which greatly exceeds normal user locked_vm settings that are generally in the kb to mb range. However, if root is used, then accounting isn't done, and then it's possible to hit this issue.
Link: https://lore.kernel.org/all/6895b298.050a0220.7f033.0059.GAE@google.com/ Cc: stable@vger.kernel.org Reported-by: syzbot+23727438116feb13df15@syzkaller.appspotmail.com Fixes: 087f997870a9 ("io_uring/memmap: implement mmap for regions") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/memmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/io_uring/memmap.c +++ b/io_uring/memmap.c @@ -156,7 +156,7 @@ static int io_region_allocate_pages(stru unsigned long mmap_offset) { gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN; - unsigned long size = mr->nr_pages << PAGE_SHIFT; + size_t size = (size_t) mr->nr_pages << PAGE_SHIFT; unsigned long nr_allocated; struct page **pages; void *p;