[PATCH 4.9 13/63] ib_srpt: Fix a use-after-free in srpt_close_ch()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@xxxxxxx>

commit 995250959d22fc341b5424e3343b0ce5df672461 upstream.

Avoid that KASAN reports the following:

BUG: KASAN: use-after-free in srpt_close_ch+0x4f/0x1b0 [ib_srpt]
Read of size 4 at addr ffff880151180cb8 by task check/4681

CPU: 15 PID: 4681 Comm: check Not tainted 4.18.0-rc2-dbg+ #4
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
Call Trace:
 dump_stack+0xa4/0xf5
 print_address_description+0x6f/0x270
 kasan_report+0x241/0x360
 __asan_load4+0x78/0x80
 srpt_close_ch+0x4f/0x1b0 [ib_srpt]
 srpt_set_enabled+0xf7/0x1e0 [ib_srpt]
 srpt_tpg_enable_store+0xb8/0x120 [ib_srpt]
 configfs_write_file+0x14e/0x1d0 [configfs]
 __vfs_write+0xd2/0x3b0
 vfs_write+0x101/0x270
 ksys_write+0xab/0x120
 __x64_sys_write+0x43/0x50
 do_syscall_64+0x77/0x230
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: aaf45bd83eba ("IB/srpt: Detect session shutdown reliably")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/ulp/srpt/ib_srpt.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -1701,8 +1701,7 @@ static bool srpt_close_ch(struct srpt_rd
 	int ret;
 
 	if (!srpt_set_ch_state(ch, CH_DRAINING)) {
-		pr_debug("%s-%d: already closed\n", ch->sess_name,
-			 ch->qp->qp_num);
+		pr_debug("%s: already closed\n", ch->sess_name);
 		return false;
 	}