RDMA/core: Save kernel caller name when creating CQ using ib_create_cq()

Few kernel applications like SCST-iSER create CQ using ib_create_cq(),
where accessing CQ structures using rdma restrack tool leads to below NULL
pointer dereference. This patch saves caller kernel module name similar to
ib_alloc_cq().

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff8132ca70>] skip_spaces+0x30/0x30
PGD 738bac067 PUD 8533f0067 PMD 0
Oops: 0000 [#1] SMP
R10: ffff88017fc03300 R11: 0000000000000246 R12: 0000000000000000
R13: ffff88082fa5a668 R14: ffff88017475a000 R15: 0000000000000000
FS:  00002b32726582c0(0000) GS:ffff88087fc40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000008491a1000 CR4: 00000000003607e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 [<ffffffffc05af69c>] ? fill_res_name_pid+0x7c/0x90 [ib_core]
 [<ffffffffc05af79f>] fill_res_cq_entry+0xef/0x170 [ib_core]
 [<ffffffffc05af4c4>] res_get_common_dumpit+0x3c4/0x480 [ib_core]
 [<ffffffffc05af5d3>] nldev_res_get_cq_dumpit+0x13/0x20 [ib_core]
 [<ffffffff815bc1e7>] netlink_dump+0x117/0x2e0
 [<ffffffff815bcb8b>] __netlink_dump_start+0x1ab/0x230
 [<ffffffffc059fead>] ibnl_rcv_msg+0x11d/0x1f0 [ib_core]
 [<ffffffffc05af5c0>] ? nldev_res_get_mr_dumpit+0x20/0x20 [ib_core]
 [<ffffffffc059fd90>] ? rdma_nl_multicast+0x30/0x30 [ib_core]
 [<ffffffff815bea49>] netlink_rcv_skb+0xa9/0xc0
 [<ffffffffc05a0018>] ibnl_rcv+0x98/0xb0 [ib_core]
 [<ffffffff815be132>] netlink_unicast+0xf2/0x1b0
 [<ffffffff815be50f>] netlink_sendmsg+0x31f/0x6a0
 [<ffffffff8156b580>] sock_sendmsg+0xb0/0xf0
 [<ffffffff816ace9e>] ? _raw_spin_unlock_bh+0x1e/0x20
 [<ffffffff8156f998>] ? release_sock+0x118/0x170
 [<ffffffff8156b731>] SYSC_sendto+0x121/0x1c0
 [<ffffffff81568340>] ? sock_alloc_file+0xa0/0x140
 [<ffffffff81221265>] ? __fd_install+0x25/0x60
 [<ffffffff8156c2ce>] SyS_sendto+0xe/0x10
 [<ffffffff816b6c2a>] system_call_fastpath+0x16/0x1b
RIP  [<ffffffff8132ca70>] skip_spaces+0x30/0x30
RSP <ffff88072be97760>
CR2: 0000000000000000

Cc: <stable@vger.kernel.org>
Fixes: f66c8ba4 ("RDMA/core: Save kernel caller name when creating PD and CQ objects")
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Potnuri Bharat Teja <bharat@chelsio.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/verbs.c

@@ -1562,11 +1562,12 @@ EXPORT_SYMBOL(ib_destroy_qp);
 
 /* Completion queues */
 
-struct ib_cq *ib_create_cq(struct ib_device *device,
-			   ib_comp_handler comp_handler,
-			   void (*event_handler)(struct ib_event *, void *),
-			   void *cq_context,
-			   const struct ib_cq_init_attr *cq_attr)
+struct ib_cq *__ib_create_cq(struct ib_device *device,
+			     ib_comp_handler comp_handler,
+			     void (*event_handler)(struct ib_event *, void *),
+			     void *cq_context,
+			     const struct ib_cq_init_attr *cq_attr,
+			     const char *caller)
 {
 	struct ib_cq *cq;
 
@@ -1580,12 +1581,13 @@ struct ib_cq *ib_create_cq(struct ib_device *device,
 		cq->cq_context    = cq_context;
 		atomic_set(&cq->usecnt, 0);
 		cq->res.type = RDMA_RESTRACK_CQ;
+		cq->res.kern_name = caller;
 		rdma_restrack_add(&cq->res);
 	}
 
 	return cq;
 }
-EXPORT_SYMBOL(ib_create_cq);
+EXPORT_SYMBOL(__ib_create_cq);
 
 int rdma_set_cq_moderation(struct ib_cq *cq, u16 cq_count, u16 cq_period)
 {

include/rdma/ib_verbs.h

@@ -3394,11 +3394,14 @@ int ib_process_cq_direct(struct ib_cq *cq, int budget);
  *
  * Users can examine the cq structure to determine the actual CQ size.
  */
-struct ib_cq *ib_create_cq(struct ib_device *device,
-			   ib_comp_handler comp_handler,
-			   void (*event_handler)(struct ib_event *, void *),
-			   void *cq_context,
-			   const struct ib_cq_init_attr *cq_attr);
+struct ib_cq *__ib_create_cq(struct ib_device *device,
+			     ib_comp_handler comp_handler,
+			     void (*event_handler)(struct ib_event *, void *),
+			     void *cq_context,
+			     const struct ib_cq_init_attr *cq_attr,
+			     const char *caller);
+#define ib_create_cq(device, cmp_hndlr, evt_hndlr, cq_ctxt, cq_attr) \
+	__ib_create_cq((device), (cmp_hndlr), (evt_hndlr), (cq_ctxt), (cq_attr), KBUILD_MODNAME)
 
 /**
  * ib_resize_cq - Modifies the capacity of the CQ.