Re: FAILED: patch "[PATCH] nbd: always initialize struct msghdr completely" failed to apply to 6.1-stable tree

[Jens Axboe <axboe@kernel.dk>]

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On 1/26/24 3:14 PM, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 6.1-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
> git checkout FETCH_HEAD
> git cherry-pick -x 78fbb92af27d0982634116c7a31065f24d092826
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024012655-dwelled-unlinked-8b2c@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Here's the patch for 6.1-stable.

-- 
Jens Axboe


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From 53a5a05195516274e37ebefa023bcaef003a1da4 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 26 Jan 2024 20:59:08 -0700
Subject: [PATCH] nbd: always initialize struct msghdr completely

commit 78fbb92af27d0982634116c7a31065f24d092826 upstream.

syzbot complains that msg->msg_get_inq value can be uninitialized [1]

struct msghdr got many new fields recently, we should always make
sure their values is zero by default.

[1]
 BUG: KMSAN: uninit-value in tcp_recvmsg+0x686/0xac0 net/ipv4/tcp.c:2571
  tcp_recvmsg+0x686/0xac0 net/ipv4/tcp.c:2571
  inet_recvmsg+0x131/0x580 net/ipv4/af_inet.c:879
  sock_recvmsg_nosec net/socket.c:1044 [inline]
  sock_recvmsg+0x12b/0x1e0 net/socket.c:1066
  __sock_xmit+0x236/0x5c0 drivers/block/nbd.c:538
  nbd_read_reply drivers/block/nbd.c:732 [inline]
  recv_work+0x262/0x3100 drivers/block/nbd.c:863
  process_one_work kernel/workqueue.c:2627 [inline]
  process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2700
  worker_thread+0xf45/0x1490 kernel/workqueue.c:2781
  kthread+0x3ed/0x540 kernel/kthread.c:388
  ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
  ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

Local variable msg created at:
  __sock_xmit+0x4c/0x5c0 drivers/block/nbd.c:513
  nbd_read_reply drivers/block/nbd.c:732 [inline]
  recv_work+0x262/0x3100 drivers/block/nbd.c:863

CPU: 1 PID: 7465 Comm: kworker/u5:1 Not tainted 6.7.0-rc7-syzkaller-00041-gf016f7547aee #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Workqueue: nbd5-recv recv_work

Fixes: f94fd25cb0aa ("tcp: pass back data left in socket after receive")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: stable@vger.kernel.org
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: nbd@other.debian.org
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240112132657.647112-1-edumazet@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 drivers/block/nbd.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 8037aaefeb2e..9a53165de4ce 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -494,7 +494,7 @@ static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
 		       struct iov_iter *iter, int msg_flags, int *sent)
 {
 	int result;
-	struct msghdr msg;
+	struct msghdr msg = { };
 	unsigned int noreclaim_flag;
 
 	if (unlikely(!sock)) {
@@ -509,10 +509,6 @@ static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
 	noreclaim_flag = memalloc_noreclaim_save();
 	do {
 		sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
-		msg.msg_name = NULL;
-		msg.msg_namelen = 0;
-		msg.msg_control = NULL;
-		msg.msg_controllen = 0;
 		msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 
 		if (send)
-- 
2.43.0