In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix panic when calling skb_linearize The panic can be reproduced by executing the command: ./bench sockmap -c 2 -p 1 -a --rx-verdict-ingress --rx-strp 100000 Then a kernel panic was captured: ''' [ 657.460555] kernel BUG at net/core/skbuff.c:2178! [ 657.462680] Tainted: [W]=WARN [ 657.463287] Workqueue: events sk_psock_backlog ... [ 657.469610] <TASK> [ 657.469738] ? die+0x36/0x90 [ 657.469916] ? do_trap+0x1d0/0x270 [ 657.470118] ? pskb_expand_head+0x612/0xf40 [ 657.470376] ? pskb_expand_head+0x612/0xf40 [ 657.470620] ? do_error_trap+0xa3/0x170 [ 657.470846] ? pskb_expand_head+0x612/0xf40 [ 657.471092] ? handle_invalid_op+0x2c/0x40 [ 657.471335] ? pskb_expand_head+0x612/0xf40 [ 657.471579] ? exc_invalid_op+0x2d/0x40 [ 657.471805] ? asm_exc_invalid_op+0x1a/0x20 [ 657.472052] ? pskb_expand_head+0xd1/0xf40 [ 657.472292] ? pskb_expand_head+0x612/0xf40 [ 657.472540] ? lock_acquire+0x18f/0x4e0 [ 657.472766] ? find_held_lock+0x2d/0x110 [ 657.472999] ? __pfx_pskb_expand_head+0x10/0x10 [ 657.473263] ? __kmalloc_cache_noprof+0x5b/0x470 [ 657.473537] ? __pfx___lock_release.isra.0+0x10/0x10 [ 657.473826] __pskb_pull_tail+0xfd/0x1d20 [ 657.474062] ? __kasan_slab_alloc+0x4e/0x90 [ 657.474707] sk_psock_skb_ingress_enqueue+0x3bf/0x510 [ 657.475392] ? __kasan_kmalloc+0xaa/0xb0 [ 657.476010] sk_psock_backlog+0x5cf/0xd70 [ 657.476637] process_one_work+0x858/0x1a20 ''' The panic originates from the assertion BUG_ON(skb_shared(skb)) in skb_linearize(). A previous commit(see Fixes tag) introduced skb_get() to avoid race conditions between skb operations in the backlog and skb release in the recvmsg path. However, this caused the panic to always occur when skb_linearize is executed. The "--rx-strp 100000" parameter forces the RX path to use the strparser module which aggregates data until it reaches 100KB before calling sockmap logic. The 100KB payload...
4.13.0-16.193.11.0-12.195.3.0-18.195.3.0-24.265.4.0-9.125.13.0-19.194.2.0-16.194.2.0-17.214.2.0-19.234.3.0-1.104.3.0-2.114.3.0-5.164.3.0-6.174.3.0-7.184.4.0-2.166.5.0-9.96.6.0-14.146.8.0-11.116.8.0-20.206.8.0-22.226.8.0-28.286.8.0-31.316.8.0-35.356.8.0-36.366.8.0-38.38+21 more6.11.0-8.86.12.0-12.126.12.0-15.156.12.0-16.166.14.0-10.106.14.0-11.116.14.0-13.136.14.0-15.156.14.0-22.226.14.0-23.23+1 more5.19.0-1007.7~22.04.15.19.0-1009.9~22.04.15.19.0-1010.10~22.04.15.19.0-1011.11~22.04.15.19.0-1012.12~22.04.15.19.0-1013.13~22.04.15.19.0-1014.14~22.04.15.19.0-1015.15~22.04.16.11.0-1004.46.12.0-1002.26.12.0-1004.46.14.0-1003.36.14.0-1004.46.14.0-1005.56.14.0-1007.75.13.0-1005.6