[PATCH 5.15 056/135] RDMA/siw: Fix a condition race issue in MPA request processing

Greg Kroah-Hartman
2022-05-10T14:01:42Z

From: Cheng Xu <chengyou@linux.alibaba.com>

commit ef91271c65c12d36e4c2b61c61d4849fb6d11aa0 upstream.

The calling of siw_cm_upcall and detaching new_cep with its listen_cep
should be atomistic semantics. Otherwise siw_reject may be called in a
temporary state, e,g, siw_cm_upcall is called but the new_cep->listen_cep
has not being cleared.

This fixes a WARN:

WARNING: CPU: 7 PID: 201 at drivers/infiniband/sw/siw/siw_cm.c:255 siw_cep_put+0x125/0x130 [siw]
CPU: 2 PID: 201 Comm: kworker/u16:22 Kdump: loaded Tainted: G E 5.17.0-rc7 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: iw_cm_wq cm_work_handler [iw_cm]
RIP: 0010:siw_cep_put+0x125/0x130 [siw]
Call Trace:
<TASK>
siw_reject+0xac/0x180 [siw]
iw_cm_reject+0x68/0xc0 [iw_cm]
cm_work_handler+0x59d/0xe20 [iw_cm]
process_one_work+0x1e2/0x3b0
worker_thread+0x50/0x3a0
? rescuer_thread+0x390/0x390
kthread+0xe5/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
</TASK>

Fixes: 6c52fdc244b5 ("rdma/siw: connection management")
Link: https://lore.kernel.org/r/d528d83466c44687f3872eadcb8c184528b2e2d4.1650526554.git.chengyou@linux.alibaba.com
Reported-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Cheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/infiniband/sw/siw/siw_cm.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/infiniband/sw/siw/siw_cm.c
+++ b/drivers/infiniband/sw/siw/siw_cm.c
@@ -968,14 +968,15 @@ static void siw_accept_newconn(struct si

siw_cep_set_inuse(new_cep);
rv = siw_proc_mpareq(new_cep);
- siw_cep_set_free(new_cep);
-
if (rv != -EAGAIN) {
siw_cep_put(cep);
new_cep->listen_cep = NULL;
- if (rv)
+ if (rv) {
+ siw_cep_set_free(new_cep);
goto error;
+ }
}
+ siw_cep_set_free(new_cep);
}
return;