Commit 40532b29 authored Nov 20, 2023 by Keith Busch Committed by Greg Kroah-Hartman Dec 08, 2023

io_uring: fix off-by one bvec index



commit d6fef34ee4d102be448146f24caf96d7b4a05401 upstream.

If the offset equals the bv_len of the first registered bvec, then the
request does not include any of that first bvec. Skip it so that drivers
don't have to deal with a zero length bvec, which was observed to break
NVMe's PRP list creation.

Cc: stable@vger.kernel.org
Fixes: bd11b3a3 ("io_uring: don't use iov_iter_advance() for fixed buffers")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9e7f410f

fs/io_uring.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1256,7 +1256,7 @@ static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
		*/
		const struct bio_vec *bvec = imu->bvec;

		if (offset <= bvec->bv_len) {
		if (offset < bvec->bv_len) {
		iov_iter_advance(iter, offset);
		} else {
		unsigned long seg_skip;