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From: Eric Dumazet <edumazet@google.com>
Date: Sun, 3 Mar 2024 14:53:03 +0100
Message-ID: <CANn89i+fJis6omMAuEmgkFy7iND97cA8WecRSVG6P=z15DpHnQ@mail.gmail.com>
Subject: Re: [PATCH] skbuff: fix uninit-value in nr_route_frame
To: Edward Adam Davis <eadavis@qq.com>
Cc: syzbot+f770ce3566e60e5573ac@syzkaller.appspotmail.com, davem@davemloft.net, 
	kuba@kernel.org, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, 
	netdev@vger.kernel.org, pabeni@redhat.com, ralf@linux-mips.org, 
	syzkaller-bugs@googlegroups.com
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On Sun, Mar 3, 2024 at 2:24=E2=80=AFPM Edward Adam Davis <eadavis@qq.com> w=
rote:
>
> [Syzbot reported]
> BUG: KMSAN: uninit-value in nr_route_frame+0x4a9/0xfc0 net/netrom/nr_rout=
e.c:787
>  nr_route_frame+0x4a9/0xfc0 net/netrom/nr_route.c:787
>  nr_xmit+0x5a/0x1c0 net/netrom/nr_dev.c:144
>  __netdev_start_xmit include/linux/netdevice.h:4980 [inline]
>  netdev_start_xmit include/linux/netdevice.h:4994 [inline]
>  xmit_one net/core/dev.c:3547 [inline]
>  dev_hard_start_xmit+0x244/0xa10 net/core/dev.c:3563
>  __dev_queue_xmit+0x33ed/0x51c0 net/core/dev.c:4351
>  dev_queue_xmit include/linux/netdevice.h:3171 [inline]
>  raw_sendmsg+0x64e/0xc10 net/ieee802154/socket.c:299
>  ieee802154_sock_sendmsg+0x91/0xc0 net/ieee802154/socket.c:96
>  sock_sendmsg_nosec net/socket.c:730 [inline]
>  __sock_sendmsg net/socket.c:745 [inline]
>  ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
>  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
>  __sys_sendmsg net/socket.c:2667 [inline]
>  __do_sys_sendmsg net/socket.c:2676 [inline]
>  __se_sys_sendmsg net/socket.c:2674 [inline]
>  __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> Uninit was created at:
>  slab_post_alloc_hook mm/slub.c:3819 [inline]
>  slab_alloc_node mm/slub.c:3860 [inline]
>  kmem_cache_alloc_node+0x5cb/0xbc0 mm/slub.c:3903
>  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
>  __alloc_skb+0x352/0x790 net/core/skbuff.c:651
>  alloc_skb include/linux/skbuff.h:1296 [inline]
>  alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6394
>  sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2783
>  sock_alloc_send_skb include/net/sock.h:1855 [inline]
>  raw_sendmsg+0x367/0xc10 net/ieee802154/socket.c:282
>  ieee802154_sock_sendmsg+0x91/0xc0 net/ieee802154/socket.c:96
>  sock_sendmsg_nosec net/socket.c:730 [inline]
>  __sock_sendmsg net/socket.c:745 [inline]
>  ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
>  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
>  __sys_sendmsg net/socket.c:2667 [inline]
>  __do_sys_sendmsg net/socket.c:2676 [inline]
>  __se_sys_sendmsg net/socket.c:2674 [inline]
>  __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> [Fix]
> Let's clear all skb data at alloc time.

This can not be serious.

>
> Reported-and-tested-by: syzbot+f770ce3566e60e5573ac@syzkaller.appspotmail=
com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>


Fix net/netrom instead.