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[35.236.206.96]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-46a3eb336a9sm114534231cf.80.2024.12.31.02.56.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Dec 2024 02:56:06 -0800 (PST) Date: Tue, 31 Dec 2024 05:56:06 -0500 From: Willem de Bruijn To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, Simon Horman , Willem de Bruijn , eric.dumazet@gmail.com, Eric Dumazet , syzbot+74f70bb1cb968bf09e4f@syzkaller.appspotmail.com, Chengen Du Message-ID: <6773cdc68ea38_534e22949a@willemb.c.googlers.com.notmuch> In-Reply-To: <20241230161004.2681892-2-edumazet@google.com> References: <20241230161004.2681892-1-edumazet@google.com> <20241230161004.2681892-2-edumazet@google.com> Subject: Re: [PATCH net] af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Eric Dumazet wrote: > Blamed commit forgot MSG_PEEK case, allowing a crash [1] as found > by syzbot. > > Rework vlan_get_protocol_dgram() to not touch skb at all, > so that it can be used from many cpus on the same skb. > > Add a const qualifier to skb argument. > > [1] > skbuff: skb_under_panic: text:ffffffff8a8ccd05 len:29 put:14 head:ffff88807fc8e400 data:ffff88807fc8e3f4 tail:0x11 end:0x140 dev: > ------------[ cut here ]------------ > kernel BUG at net/core/skbuff.c:206 ! > Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI > CPU: 1 UID: 0 PID: 5892 Comm: syz-executor883 Not tainted 6.13.0-rc4-syzkaller-00054-gd6ef8b40d075 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > RIP: 0010:skb_panic net/core/skbuff.c:206 [inline] > RIP: 0010:skb_under_panic+0x14b/0x150 net/core/skbuff.c:216 > Code: 0b 8d 48 c7 c6 86 d5 25 8e 48 8b 54 24 08 8b 0c 24 44 8b 44 24 04 4d 89 e9 50 41 54 41 57 41 56 e8 5a 69 79 f7 48 83 c4 20 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 > RSP: 0018:ffffc900038d7638 EFLAGS: 00010282 > RAX: 0000000000000087 RBX: dffffc0000000000 RCX: 609ffd18ea660600 > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > RBP: ffff88802483c8d0 R08: ffffffff817f0a8c R09: 1ffff9200071ae60 > R10: dffffc0000000000 R11: fffff5200071ae61 R12: 0000000000000140 > R13: ffff88807fc8e400 R14: ffff88807fc8e3f4 R15: 0000000000000011 > FS: 00007fbac5e006c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fbac5e00d58 CR3: 000000001238e000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > skb_push+0xe5/0x100 net/core/skbuff.c:2636 > vlan_get_protocol_dgram+0x165/0x290 net/packet/af_packet.c:585 > packet_recvmsg+0x948/0x1ef0 net/packet/af_packet.c:3552 > sock_recvmsg_nosec net/socket.c:1033 [inline] > sock_recvmsg+0x22f/0x280 net/socket.c:1055 > ____sys_recvmsg+0x1c6/0x480 net/socket.c:2803 > ___sys_recvmsg net/socket.c:2845 [inline] > do_recvmmsg+0x426/0xab0 net/socket.c:2940 > __sys_recvmmsg net/socket.c:3014 [inline] > __do_sys_recvmmsg net/socket.c:3037 [inline] > __se_sys_recvmmsg net/socket.c:3030 [inline] > __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3030 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Fixes: 79eecf631c14 ("af_packet: Handle outgoing VLAN packets without hardware offloading") > Reported-by: syzbot+74f70bb1cb968bf09e4f@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/6772c485.050a0220.2f3838.04c5.GAE@google.com/T/#u > Signed-off-by: Eric Dumazet > Cc: Chengen Du > Cc: Willem de Bruijn Reviewed-by: Willem de Bruijn