CVE-2024-57901

In the Linux kernel, the following vulnerability has been resolved:

af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK

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:<NULL>

------------[ 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:

<TASK>

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