Messages in this thread | | | Date | Thu, 18 Jan 2024 10:07:01 +0800 | Subject | Re: [PATCH net] net/smc: fix illegal rmb_desc access in SMC-D connection dump | From | Wen Gu <> |
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On 2024/1/18 09:50, Dust Li wrote: > On Wed, Jan 17, 2024 at 08:27:49PM +0800, Wen Gu wrote: >> 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: ce51f63e63c5 ("net/smc: Prevent kernel-infoleak in __smc_diag_dump()") > > ce51f63e63c5 ("net/smc: Prevent kernel-infoleak in __smc_diag_dump()") > only add a memset() of 'struct smcd_diag_dmbinfo dinfo', which I don't > think is not the real cause of the bug. >
After re-checking the definition of Fixes tag, I agree that ce51f63e63c5 is not appropriate and 4b1b7d3b30a6 ("net/smc: add SMC-D diag support") should be used.
Thank you!
>> Signed-off-by: Wen Gu <guwen@linux.alibaba.com> >> --- >> 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 52f7c4f1e767..5a33908015f3 100644 >> --- a/net/smc/smc_diag.c >> +++ b/net/smc/smc_diag.c >> @@ -164,7 +164,7 @@ static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb, >> } >> if (smc_conn_lgr_valid(&smc->conn) && 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; >> struct smcd_dev *smcd = conn->lgr->smcd; >> -- >> 2.43.0
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