From: Sharath Srinivasan <sharath.sriniva...@oracle.com>
struct rdma_cm_id has member "struct work_struct net_work"
that is reused for enqueuing cma_netevent_work_handler()s
onto cma_wq.
Below crash[1] can occur if more than one call to
cma_netevent_callback() occurs in quick succession,
which further enqueues cma_netevent_work_handler()s for the
same rdma_cm_id, overwriting any previously queued work-item(s)
that was just scheduled to run i.e. there is no guarantee
the queued work item may run between two successive calls
to cma_netevent_callback() and the 2nd INIT_WORK would overwrite
the 1st work item (for the same rdma_cm_id), despite grabbing
id_table_lock during enqueue.
Also drgn analysis [2] indicates the work item was likely overwritten.
Fix this by moving the INIT_WORK() to __rdma_create_id(),
so that it doesn't race with any existing queue_work() or
its worker thread.
[1] Trimmed crash stack:
=============================================
BUG: kernel NULL pointer dereference, address: 0000000000000008
kworker/u256:6 ... 6.12.0-0...
Workqueue: cma_netevent_work_handler [rdma_cm] (rdma_cm)
RIP: 0010:process_one_work+0xba/0x31a
Call Trace:
worker_thread+0x266/0x3a0
kthread+0xcf/0x100
ret_from_fork+0x31/0x50
ret_from_fork_asm+0x1a/0x30
=============================================
[2] drgn crash analysis:
>>> trace = prog.crashed_thread().stack_trace()
>>> trace
(0) crash_setup_regs (./arch/x86/include/asm/kexec.h:111:15)
(1) __crash_kexec (kernel/crash_core.c:122:4)
(2) panic (kernel/panic.c:399:3)
(3) oops_end (arch/x86/kernel/dumpstack.c:382:3)
...
(8) process_one_work (kernel/workqueue.c:3168:2)
(9) process_scheduled_works (kernel/workqueue.c:3310:3)
(10) worker_thread (kernel/workqueue.c:3391:4)
(11) kthread (kernel/kthread.c:389:9)
Line workqueue.c:3168 for this kernel version is in process_one_work():
3168 strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN);
>>> trace[8]["work"]
*(struct work_struct *)0xffff92577d0a21d8 = {
.data = (atomic_long_t){
.counter = (s64)536870912, <=== Note
},
.entry = (struct list_head){
.next = (struct list_head *)0xffff924d075924c0,
.prev = (struct list_head *)0xffff924d075924c0,
},
.func = (work_func_t)cma_netevent_work_handler+0x0 = 0xffffffffc2cec280,
}
Suspicion is that pwq is NULL:
>>> trace[8]["pwq"]
(struct pool_workqueue *)<absent>
In process_one_work(), pwq is assigned from:
struct pool_workqueue *pwq = get_work_pwq(work);
and get_work_pwq() is:
static struct pool_workqueue *get_work_pwq(struct work_struct *work)
{
unsigned long data = atomic_long_read(&work->data);
if (data & WORK_STRUCT_PWQ)
return work_struct_pwq(data);
else
return NULL;
}
WORK_STRUCT_PWQ is 0x4:
>>> print(repr(prog['WORK_STRUCT_PWQ']))
Object(prog, 'enum work_flags', value=4)
But work->data is 536870912 which is 0x20000000.
So, get_work_pwq() returns NULL and we crash in process_one_work():
3168 strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN);
=============================================
Fixes: 925d046e7e52 ("RDMA/core: Add a netevent notifier to cma")
Cc: sta...@vger.kernel.org
Co-developed-by: Håkon Bugge <haakon.bu...@oracle.com>
Signed-off-by: Håkon Bugge <haakon.bu...@oracle.com>
Signed-off-by: Sharath Srinivasan <sharath.sriniva...@oracle.com>
Reviewed-by: Patrisious Haddad <phad...@nvidia.com>
Link: https://patch.msgid.link/bf0082f9-5b25-4593-92c6-d130aa8ba...@oracle.com
Signed-off-by: Leon Romanovsky <l...@kernel.org>
https://virtuozzo.atlassian.net/browse/ASUP-1636
(cherry picked from commit 45f5dcdd049719fb999393b30679605f16ebce14)
Signed-off-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
---
drivers/infiniband/core/cma.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 5da1725d96d4..906c03f6eabb 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -72,6 +72,8 @@ static const char * const cma_events[] = {
static void cma_iboe_set_mgid(struct sockaddr *addr, union ib_gid *mgid,
enum ib_gid_type gid_type);
+static void cma_netevent_work_handler(struct work_struct *_work);
+
const char *__attribute_const__ rdma_event_msg(enum rdma_cm_event_type event)
{
size_t index = event;
@@ -993,6 +995,7 @@ __rdma_create_id(struct net *net, rdma_cm_event_handler
event_handler,
get_random_bytes(&id_priv->seq_num, sizeof id_priv->seq_num);
id_priv->id.route.addr.dev_addr.net = get_net(net);
id_priv->seq_num &= 0x00ffffff;
+ INIT_WORK(&id_priv->id.net_work, cma_netevent_work_handler);
rdma_restrack_new(&id_priv->res, RDMA_RESTRACK_CM_ID);
if (parent)
@@ -5187,7 +5190,6 @@ static int cma_netevent_callback(struct notifier_block
*self,
if (!memcmp(current_id->id.route.addr.dev_addr.dst_dev_addr,
neigh->ha, ETH_ALEN))
continue;
- INIT_WORK(¤t_id->id.net_work, cma_netevent_work_handler);
cma_id_get(current_id);
queue_work(cma_wq, ¤t_id->id.net_work);
}
--
2.49.0
_______________________________________________
Devel mailing list
Devel@openvz.org
https://lists.openvz.org/mailman/listinfo/devel
