4.19-stable review patch. If anyone has any objections, please let me know.
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From: Wen Gu guwen@linux.alibaba.com
[ Upstream commit dbc153fd3c142909e564bb256da087e13fbf239c ]
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.
Fixes: 4b1b7d3b30a6 ("net/smc: add SMC-D diag support") Signed-off-by: Wen Gu guwen@linux.alibaba.com Reviewed-by: Dust Li dust.li@linux.alibaba.com Reviewed-by: Wenjia Zhang wenjia@linux.ibm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/smc/smc_diag.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/smc/smc_diag.c b/net/smc/smc_diag.c index 6c4a7a5938b7..3ab14678afff 100644 --- a/net/smc/smc_diag.c +++ b/net/smc/smc_diag.c @@ -167,7 +167,7 @@ static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb, } if (smc->conn.lgr && smc->conn.lgr->is_smcd && (req->diag_ext & (1 << (SMC_DIAG_DMBINFO - 1))) && - !list_empty(&smc->conn.lgr->list)) { + !list_empty(&smc->conn.lgr->list) && smc->conn.rmb_desc) { struct smc_connection *conn = &smc->conn; struct smcd_diag_dmbinfo dinfo;