[PATCH for-next 1/6] RDMA/bnxt_re: Avoid freeing MR resources if dereg fails

[Selvin Xavier <selvin.xavier@broadcom.com>]

Driver returns error code for MR dereg, but frees the MR structure.
When the MR dereg is retried due to previous error, the system crashes
as the structure is already freed.

[45545.547748] BUG: unable to handle kernel NULL pointer dereference at 00000000000001b8
[45545.557020] PGD 0 P4D 0
[45545.560370] Oops: 0000 [#1] SMP PTI
[45545.564778] CPU: 7 PID: 12178 Comm: ib_send_bw Kdump: loaded Not tainted 4.18.0-124.el8.x86_64 #1
[45545.575211] Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.1.10 03/10/2015
[45545.584202] RIP: 0010:__dev_printk+0x2a/0x70
[45545.589495] Code: 0f 1f 44 00 00 49 89 d1 48 85 f6 0f 84 f6 2b 00 00 4c 8b 46 70 4d 85 c0 75 04 4c 8b
46 10 48 8b 86 a8 00 00 00 48 85 c0 74 16 <48> 8b 08 0f be 7f 01 48 c7 c2 13 ac ac 83 83 ef 30 e9 10 fe ff ff
[45545.611538] RSP: 0018:ffffaf7c04607a60 EFLAGS: 00010006
[45545.617903] RAX: 00000000000001b8 RBX: ffffa0010c91c488 RCX: 0000000000000246
[45545.626416] RDX: ffffaf7c04607a68 RSI: ffffa0010c91caa8 RDI: ffffffff83a788eb
[45545.634929] RBP: ffffaf7c04607ac8 R08: 0000000000000000 R09: ffffaf7c04607a68
[45545.643433] R10: 0000000000000000 R11: 0000000000000001 R12: ffffaf7c04607b90
[45545.651924] R13: 000000000000000e R14: 0000000000000000 R15: 00000000ffffa001
[45545.660411] FS:  0000146fa1f1cdc0(0000) GS:ffffa0012fac0000(0000) knlGS:0000000000000000
[45545.669969] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[45545.676910] CR2: 00000000000001b8 CR3: 000000007680a003 CR4: 00000000001606e0
[45545.685405] Call Trace:
[45545.688661]  dev_err+0x6c/0x90
[45545.692592]  ? dev_printk_emit+0x4e/0x70
[45545.697490]  bnxt_qplib_rcfw_send_message+0x594/0x660 [bnxt_re]
[45545.704619]  ? dev_err+0x6c/0x90
[45545.708727]  bnxt_qplib_free_mrw+0x80/0xe0 [bnxt_re]
[45545.714782]  bnxt_re_dereg_mr+0x2e/0xd0 [bnxt_re]
[45545.720552]  ib_dereg_mr+0x2f/0x50 [ib_core]
[45545.725835]  destroy_hw_idr_uobject+0x20/0x70 [ib_uverbs]
[45545.732375]  uverbs_destroy_uobject+0x2e/0x170 [ib_uverbs]
[45545.739010]  __uverbs_cleanup_ufile+0x6e/0x90 [ib_uverbs]
[45545.745544]  uverbs_destroy_ufile_hw+0x61/0x130 [ib_uverbs]
[45545.752272]  ib_uverbs_close+0x1f/0x80 [ib_uverbs]
[45545.758126]  __fput+0xb7/0x230
[45545.762033]  task_work_run+0x8a/0xb0
[45545.766518]  do_exit+0x2da/0xb40
...
[45545.841546] RIP: 0033:0x146fa113a387
[45545.845934] Code: Bad RIP value.
[45545.849931] RSP: 002b:00007fff945d1478 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff02
[45545.858783] RAX: 0000000000000000 RBX: 000055a248908d70 RCX: 0000000000000000
[45545.867145] RDX: 0000146fa1f2b000 RSI: 0000000000000001 RDI: 000055a248906488
[45545.875503] RBP: 000055a248909630 R08: 0000000000010000 R09: 0000000000000000
[45545.883849] R10: 0000000000000000 R11: 0000000000000000 R12: 000055a248906488
[45545.892180] R13: 0000000000000001 R14: 0000000000000000 R15: 000055a2489095f0

Do not free the MR structures, when driver returns error to the stack.

Fixes: 872f3578241d ("RDMA/bnxt_re: Add support for MRs with Huge pages")
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
---
 drivers/infiniband/hw/bnxt_re/ib_verbs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/bnxt_re/ib_verbs.c b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
index 9b6ca15..ad5112a 100644
--- a/drivers/infiniband/hw/bnxt_re/ib_verbs.c
+++ b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
@@ -3305,8 +3305,10 @@ int bnxt_re_dereg_mr(struct ib_mr *ib_mr, struct ib_udata *udata)
 	int rc;
 
 	rc = bnxt_qplib_free_mrw(&rdev->qplib_res, &mr->qplib_mr);
-	if (rc)
+	if (rc) {
 		dev_err(rdev_to_dev(rdev), "Dereg MR failed: %#x\n", rc);
+		return rc;
+	}
 
 	if (mr->pages) {
 		rc = bnxt_qplib_free_fast_reg_page_list(&rdev->qplib_res,
-- 
2.5.5