diff mbox series

tun: honor IOCB_NOWAIT flag

Message ID e9451860-96cc-c7c7-47b8-fe42cadd5f4c@kernel.dk (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series tun: honor IOCB_NOWAIT flag | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Guessed tree name to be net-next
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 33 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable fail Stable CC detected: Cc: stable@vger.kernel.org

Commit Message

Jens Axboe Nov. 20, 2020, 2:59 p.m. UTC
tun only checks the file O_NONBLOCK flag, but it should also be checking
the iocb IOCB_NOWAIT flag. Any fops using ->read/write_iter() should check
both, otherwise it breaks users that correctly expect O_NONBLOCK semantics
if IOCB_NOWAIT is set.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

Had a bug report on io_uring, and it's due to tun not honoring
IOCB_NOWAIT. Let's get this fixed.

Comments

Jakub Kicinski Nov. 21, 2020, 11:19 p.m. UTC | #1
On Fri, 20 Nov 2020 07:59:54 -0700 Jens Axboe wrote:
> tun only checks the file O_NONBLOCK flag, but it should also be checking
> the iocb IOCB_NOWAIT flag. Any fops using ->read/write_iter() should check
> both, otherwise it breaks users that correctly expect O_NONBLOCK semantics
> if IOCB_NOWAIT is set.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

Applied, thanks!
diff mbox series

Patch

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index be69d272052f..cd06cae76035 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1961,12 +1961,15 @@  static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct tun_file *tfile = file->private_data;
 	struct tun_struct *tun = tun_get(tfile);
 	ssize_t result;
+	int noblock = 0;
 
 	if (!tun)
 		return -EBADFD;
 
-	result = tun_get_user(tun, tfile, NULL, from,
-			      file->f_flags & O_NONBLOCK, false);
+	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
+		noblock = 1;
+
+	result = tun_get_user(tun, tfile, NULL, from, noblock, false);
 
 	tun_put(tun);
 	return result;
@@ -2185,10 +2188,15 @@  static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	struct tun_file *tfile = file->private_data;
 	struct tun_struct *tun = tun_get(tfile);
 	ssize_t len = iov_iter_count(to), ret;
+	int noblock = 0;
 
 	if (!tun)
 		return -EBADFD;
-	ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK, NULL);
+
+	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
+		noblock = 1;
+
+	ret = tun_do_read(tun, tfile, to, noblock, NULL);
 	ret = min_t(ssize_t, ret, len);
 	if (ret > 0)
 		iocb->ki_pos = ret;