A syzkaller test hits a NULL pointer dereference in
rdma_resolve_route():
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7185 Comm: syz-executor670 Not tainted 4.14.147 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880a7c4c0c0 task.stack: ffff888084398000
RIP: 0010:rdma_cap_ib_sa include/rdma/ib_verbs.h:2682 [inline]
RIP: 0010:rdma_resolve_route+0x11f/0x2bf0 drivers/infiniband/core/cma.c:2678
RSP: 0018:ffff88808439fa20 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000029 RSI: 0000000000000001 RDI: 0000000000000148
RBP: ffff88808439fbc0 R08: ffff8880a7c4c0c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809f540dc0
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88809f540f78
FS: 00007f03a8778700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f03a8777e78 CR3: 000000008afd9000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
ucma_resolve_route+0xab/0x100 drivers/infiniband/core/ucma.c:740
ucma_write+0x231/0x310 drivers/infiniband/core/ucma.c:1672
__vfs_write+0x105/0x6b0 fs/read_write.c:480
vfs_write+0x198/0x500 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xfd/0x230 fs/read_write.c:582
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x446a49
RSP: 002b:00007f03a8777db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 0000000000446a49
RDX: 0000000000000010 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007ffea0dde3ef R14: 00007f03a87789c0 R15: 0000000000000000
Code: 00 48 c1 ea 03 80 3c 02 00 0f 85 ea 24 00 00 48 b8 00 00 00 00 00 fc
ff df 4d 8b 34 24 49 8d be 48 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00
0f 85 d1 24 00 00 48 b8 00 00 00 00 00 fc ff df 41
RIP: rdma_cap_ib_sa include/rdma/ib_verbs.h:2682 [inline] RSP:
ffff88808439fa20
RIP: rdma_resolve_route+0x11f/0x2bf0 drivers/infiniband/core/cma.c:2678
RSP: ffff88808439fa20
The crash is caused by a race between the CM state updates in
addr_handler() and rdma_resolve_route().
The syzkaller program executes following sequence:
1. rdma_create_id()
2. rdma_resolve_ip()
3. rdma_resolve_route()
Please note the lack of rdma_get_cm_event() between 2 and 3 above. The
following happens:
Thread 1 CM_ID state Thread 2
rdma_create_id() IDLE
rdma_resolve_ip() ADDR_QUERY
addr_handler()
ADDR_RESOLVED (set state)
rdma_resolve_route()
(check state and set to) ROUTE_QUERY
--> cma_cm_event_handler()
DESTROYING (returns error)
--> rdma_destroy_id()
--> rdma_cap_ib_sa()
(but cm_id has been destroyed)
I see two solutions; a) let addr_handler() only change the state once,
to one of ADDR_RESOLVED, ADDR_BOUND, or DESTROYING or b) add mutex
locking to rdma_resolve_addr(). b) requires addr_handler() to
relinquish the lock when calling the event handler, as the event
handler typically will call rdma_resolve_route() before returning.
The b) solution is implemented herein.
Reported-by: syzbot+69226cc89d87fd4f8f40@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/infiniband/core/cma.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 2dec3a02ab9f..45f26bc0fbfe 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2979,8 +2979,11 @@ int rdma_resolve_route(struct rdma_cm_id *id, unsigned long timeout_ms)
int ret;
id_priv = container_of(id, struct rdma_id_private, id);
- if (!cma_comp_exch(id_priv, RDMA_CM_ADDR_RESOLVED, RDMA_CM_ROUTE_QUERY))
+ mutex_lock(&id_priv->handler_mutex);
+ if (!cma_comp_exch(id_priv, RDMA_CM_ADDR_RESOLVED, RDMA_CM_ROUTE_QUERY)) {
+ mutex_unlock(&id_priv->handler_mutex);
return -EINVAL;
+ }
atomic_inc(&id_priv->refcount);
if (rdma_cap_ib_sa(id->device, id->port_num))
@@ -2995,9 +2998,12 @@ int rdma_resolve_route(struct rdma_cm_id *id, unsigned long timeout_ms)
if (ret)
goto err;
+ mutex_unlock(&id_priv->handler_mutex);
return 0;
err:
cma_comp_exch(id_priv, RDMA_CM_ROUTE_QUERY, RDMA_CM_ADDR_RESOLVED);
+ mutex_unlock(&id_priv->handler_mutex);
+
cma_deref_id(id_priv);
return ret;
}
@@ -3085,6 +3091,7 @@ static void addr_handler(int status, struct sockaddr *src_addr,
struct rdma_cm_event event = {};
struct sockaddr *addr;
struct sockaddr_storage old_addr;
+ int ret;
mutex_lock(&id_priv->handler_mutex);
if (!cma_comp_exch(id_priv, RDMA_CM_ADDR_QUERY,
@@ -3119,7 +3126,11 @@ static void addr_handler(int status, struct sockaddr *src_addr,
} else
event.event = RDMA_CM_EVENT_ADDR_RESOLVED;
- if (cma_cm_event_handler(id_priv, &event)) {
+ mutex_unlock(&id_priv->handler_mutex);
+ ret = cma_cm_event_handler(id_priv, &event);
+ mutex_lock(&id_priv->handler_mutex);
+
+ if (ret) {
cma_exch(id_priv, RDMA_CM_DESTROYING);
mutex_unlock(&id_priv->handler_mutex);
rdma_destroy_id(&id_priv->id);
--
2.20.1
