From: Wen Gu guwen@linux.alibaba.com
[ Upstream commit 71c6aa0305e3d2365d3bfd0134b4025d9e7ba388 ]
We encountered a crash when using SMCRv2. It is caused by a logical error in smc_llc_fill_ext_v2().
BUG: kernel NULL pointer dereference, address: 0000000000000014 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 7 PID: 453 Comm: kworker/7:4 Kdump: loaded Tainted: G W E 6.4.0-rc3+ #44 Workqueue: events smc_llc_add_link_work [smc] RIP: 0010:smc_llc_fill_ext_v2+0x117/0x280 [smc] RSP: 0018:ffffacb5c064bd88 EFLAGS: 00010282 RAX: ffff9a6bc1c3c02c RBX: ffff9a6be3558000 RCX: 0000000000000000 RDX: 0000000000000002 RSI: 0000000000000002 RDI: 000000000000000a RBP: ffffacb5c064bdb8 R08: 0000000000000040 R09: 000000000000000c R10: ffff9a6bc0910300 R11: 0000000000000002 R12: 0000000000000000 R13: 0000000000000002 R14: ffff9a6bc1c3c02c R15: ffff9a6be3558250 FS: 0000000000000000(0000) GS:ffff9a6eefdc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000014 CR3: 000000010b078003 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> smc_llc_send_add_link+0x1ae/0x2f0 [smc] smc_llc_srv_add_link+0x2c9/0x5a0 [smc] ? cc_mkenc+0x40/0x60 smc_llc_add_link_work+0xb8/0x140 [smc] process_one_work+0x1e5/0x3f0 worker_thread+0x4d/0x2f0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe5/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 </TASK>
When an alernate RNIC is available in system, SMC will try to add a new link based on the RNIC for resilience. All the RMBs in use will be mapped to the new link. Then the RMBs' MRs corresponding to the new link will be filled into SMCRv2 LLC ADD LINK messages.
However, smc_llc_fill_ext_v2() mistakenly accesses to unused RMBs which haven't been mapped to the new link and have no valid MRs, thus causing a crash. So this patch fixes the logic.
Fixes: b4ba4652b3f8 ("net/smc: extend LLC layer for SMC-Rv2") Signed-off-by: Wen Gu guwen@linux.alibaba.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/smc/smc_llc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c index 8423e8e0063f4..7a8d9163d186e 100644 --- a/net/smc/smc_llc.c +++ b/net/smc/smc_llc.c @@ -617,6 +617,8 @@ static int smc_llc_fill_ext_v2(struct smc_llc_msg_add_link_v2_ext *ext, goto out; buf_pos = smc_llc_get_first_rmb(lgr, &buf_lst); for (i = 0; i < ext->num_rkeys; i++) { + while (buf_pos && !(buf_pos)->used) + buf_pos = smc_llc_get_next_rmb(lgr, &buf_lst, buf_pos); if (!buf_pos) break; rmb = buf_pos; @@ -626,8 +628,6 @@ static int smc_llc_fill_ext_v2(struct smc_llc_msg_add_link_v2_ext *ext, cpu_to_be64((uintptr_t)rmb->cpu_addr) : cpu_to_be64((u64)sg_dma_address(rmb->sgt[lnk_idx].sgl)); buf_pos = smc_llc_get_next_rmb(lgr, &buf_lst, buf_pos); - while (buf_pos && !(buf_pos)->used) - buf_pos = smc_llc_get_next_rmb(lgr, &buf_lst, buf_pos); } len += i * sizeof(ext->rt[0]); out: