mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-12-27 11:06:41 -05:00
Code Issues Packages Projects Releases Wiki Activity

kcm: Fix splice support

Browse Source 
Flags passed in for splice() syscall should not end up in
skb_recv_datagram(). As SPLICE_F_NONBLOCK == MSG_PEEK, kernel gets
confused: skb isn't unlinked from a receive queue, while strp_msg::offset
and strp_msg::full_len are updated.

Unbreak the logic a bit more by mapping both O_NONBLOCK and
SPLICE_F_NONBLOCK to MSG_DONTWAIT. This way we align with man splice(2) in
regard to errno EAGAIN:

   SPLICE_F_NONBLOCK was specified in flags or one of the file descriptors
   had been marked as nonblocking (O_NONBLOCK), and the operation would
   block.

Fixes: 5121197ecc ("kcm: close race conditions on sk_receive_queue")
Fixes: 91687355b9 ("kcm: Splice support")
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://patch.msgid.link/20250725-kcm-splice-v1-1-9a725ad2ee71@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Michal Luczaj
2025-07-25 12:33:04 +02:00
committed by Jakub Kicinski
parent d9104cec3e
commit 9063de636c
1 changed files with 6 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
net/kcm/kcmsock.c
View File

@@ -19,6 +19,7 @@
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/splice.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
#include <linux/syscalls.h>
@@ -1029,6 +1030,11 @@ static ssize_t kcm_splice_read(struct socket *sock, loff_t *ppos,
ssize_t copied;
struct sk_buff *skb;
if (sock->file->f_flags & O_NONBLOCK || flags & SPLICE_F_NONBLOCK)
flags = MSG_DONTWAIT;
else
flags = 0;
/* Only support splice for SOCKSEQPACKET */
skb = skb_recv_datagram(sk, flags, &err);