Commit 8582792c authored by Sungwoo Kim's avatar Sungwoo Kim Committed by Jens Axboe
Browse files

block: bio-integrity: Fix null-ptr-deref in bio_integrity_map_user() 



pin_user_pages_fast() can partially succeed and return the number of
pages that were actually pinned. However, the bio_integrity_map_user()
does not handle this partial pinning. This leads to a general protection
fault since bvec_from_pages() dereferences an unpinned page address,
which is 0.

To fix this, add a check to verify that all requested memory is pinned.
If partial pinning occurs, unpin the memory and return -EFAULT.

Kernel Oops:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 UID: 0 PID: 1061 Comm: nvme-passthroug Not tainted 7.0.0-11783-g90957f9314e8-dirty #16 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
RIP: 0010:bio_integrity_map_user.cold+0x1b0/0x9d6

Fixes: 492c5d45 ("block: bio-integrity: directly map user buffers")
Acked-by: default avatarChao Shi <cshi008@fiu.edu>
Acked-by: default avatarWeidong Zhu <weizhu@fiu.edu>
Acked-by: default avatarDave Tian <daveti@purdue.edu>
Signed-off-by: default avatarSungwoo Kim <iam@sung-woo.kim>
Tested-by: default avatarShin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://github.com/linux-blktests/blktests/pull/244
Link: https://patch.msgid.link/20260512050929.541397-2-iam@sung-woo.kim


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2c6e6a18

block/bio-integrity.c

+18 −0
Original line number Diff line number Diff line
@@ -402,6 +402,24 @@ int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter) 
	if (unlikely(ret < 0))

		goto free_bvec;



	/*

	 * Handle partial pinning. This can happen when pin_user_pages_fast()

	 * returns fewer pages than requested.

	 */

	if (user_backed_iter(iter) && unlikely(ret != bytes)) {

		if (ret > 0) {

			int npinned = DIV_ROUND_UP(offset + ret, PAGE_SIZE);

			int i;



			for (i = 0; i < npinned; i++)

				unpin_user_page(pages[i]);

		}

		if (pages != stack_pages)

			kvfree(pages);

		ret = -EFAULT;

		goto free_bvec;

	}



	nr_bvecs = bvec_from_pages(bvec, pages, nr_vecs, bytes, offset,

				   &is_p2p);

	if (pages != stack_pages)