CVE-2024-26615net/smc: fix illegal rmb_desc access in SMC-D connection dump

Official description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix illegal rmb_desc access in SMC-D connection dump A crash was found when dumping SMC-D connections. It can be reproduced by following steps: - run nginx/wrk test: smc_run nginx smc_run wrk -t 16 -c 1000 -d <duration> -H 'Connection: Close' <URL> - continuously dump SMC-D connections in parallel: watch -n 1 'smcss -D' BUG: kernel NULL pointer dereference, address: 0000000000000030 CPU: 2 PID: 7204 Comm: smcss Kdump: loaded Tainted: G E 6.7.0+ #55 RIP: 0010:__smc_diag_dump.constprop.0+0x5e5/0x620 [smc_diag] Call Trace: <TASK> ? __die+0x24/0x70 ? page_fault_oops+0x66/0x150 ? exc_page_fault+0x69/0x140 ? asm_exc_page_fault+0x26/0x30 ? __smc_diag_dump.constprop.0+0x5e5/0x620 [smc_diag] ? __kmalloc_node_track_caller+0x35d/0x430 ? __alloc_skb+0x77/0x170 smc_diag_dump_proto+0xd0/0xf0 [smc_diag] smc_diag_dump+0x26/0x60 [smc_diag] netlink_dump+0x19f/0x320 __netlink_dump_start+0x1dc/0x300 smc_diag_handler_dump+0x6a/0x80 [smc_diag] ? __pfx_smc_diag_dump+0x10/0x10 [smc_diag] sock_diag_rcv_msg+0x121/0x140 ? __pfx_sock_diag_rcv_msg+0x10/0x10 netlink_rcv_skb+0x5a/0x110 sock_diag_rcv+0x28/0x40 netlink_unicast+0x22a/0x330 netlink_sendmsg+0x1f8/0x420 __sock_sendmsg+0xb0/0xc0 ____sys_sendmsg+0x24e/0x300 ? copy_msghdr_from_user+0x62/0x80 ___sys_sendmsg+0x7c/0xd0 ? __do_fault+0x34/0x160 ? do_read_fault+0x5f/0x100 ? do_fault+0xb0/0x110 ? __handle_mm_fault+0x2b0/0x6c0 __sys_sendmsg+0x4d/0x80 do_syscall_64+0x69/0x180 entry_SYSCALL_64_after_hwframe+0x6e/0x76 It is possible that the connection is in process of being established when we dump it. Assumed that the connection has been registered in a link group by smc_conn_create() but the rmb_desc has not yet been initialized by smc_buf_create(), thus causing the illegal access to conn->rmb_desc. So fix it by checking before dump.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/27aea64838914c6122db5b8bd4bed865c9736f22
• https://git.kernel.org/stable/c/1fea9969b81c67d0cb1611d1b8b7d19049d937be
• https://git.kernel.org/stable/c/5fed92ca32eafbfae8b6bee8ca34cca71c6a8b6d
• https://git.kernel.org/stable/c/68b888d51ac82f2b96bf5e077a31d76afcdef25a
• https://git.kernel.org/stable/c/6994dba06321e3c48fdad0ba796a063d9d82183a
• https://git.kernel.org/stable/c/a164c2922675d7051805cdaf2b07daffe44f20d9
• https://git.kernel.org/stable/c/8f3f9186e5bb96a9c9654c41653210e3ea7e48a6
• https://git.kernel.org/stable/c/dbc153fd3c142909e564bb256da087e13fbf239c
• https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html x_transferred
• https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html x_transferred