From 40532b29138e9dee9997f82f13ed36c010927882 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Mon, 20 Nov 2023 14:18:31 -0800 Subject: [PATCH] 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: bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed buffers") Signed-off-by: Keith Busch Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 3683ddeb625a..adc263400471 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -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;