6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit b13ee668e8280ca5b07f8ce2846b9957a8a10853 upstream.
blkdev_read_iter() has a few odd checks, like gating the position and count adjustment on whether or not the result is bigger-than-or-equal to zero (where bigger than makes more sense), and not checking the return value of blkdev_direct_IO() before doing an iov_iter_revert(). The latter can lead to attempting to revert with a negative value, which when passed to iov_iter_revert() as an unsigned value will lead to throwing a WARN_ON() because unroll is bigger than MAX_RW_COUNT.
Be sane and don't revert for -EIOCBQUEUED, like what is done in other spots.
Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/fops.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/block/fops.c +++ b/block/fops.c @@ -758,11 +758,12 @@ static ssize_t blkdev_read_iter(struct k file_accessed(iocb->ki_filp);
ret = blkdev_direct_IO(iocb, to); - if (ret >= 0) { + if (ret > 0) { iocb->ki_pos += ret; count -= ret; } - iov_iter_revert(to, count - iov_iter_count(to)); + if (ret != -EIOCBQUEUED) + iov_iter_revert(to, count - iov_iter_count(to)); if (ret < 0 || !count) goto reexpand; }