From: Yonatan Cohen <yonatanc@xxxxxxxxxxxx>
In the time between rxe_send has finished and skb destructor
called, the QP's ref count might be 0, leading to a possible
QP destruction. This will lead to a kernel panic when the destructor
dereferences the QP.
The operation of incrementing QP ref count at rxe_send and decrementing
from skb destructor will prevent this crash.
BUG: unable to handle kernel NULL pointer dereference at 000000000000072c
IP: [<ffffffffa05df765>] rxe_skb_tx_dtor+0x15/0x50 [rdma_rxe]
PGD 0 [16240.211178]
Oops: 0002 [#1] SMP
CPU: 3 PID: 0 Comm: swapper/3 Tainted: G OE 4.9.0-mlnx #1
Hardware name: Red Hat KVM, BIOS Bochs 01/01/2011
task: ffff88042d6b1480 task.stack: ffffc90001904000
RIP: 0010:[<ffffffffa05df765>] [<ffffffffa05df765>] rxe_skb_tx_dtor+0x15/0x50 [rdma_rxe]
RSP: 0018:ffff88043fcc3df0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff880429684700 RCX: ffff88042d248200
RDX: 00000000ffffffff RSI: 00000000fffffe01 RDI: ffff880429684700
RBP: ffff88043fcc3e00 R08: ffff88043fcda240 R09: 00000000ff2d1de6
R10: 0000000000000000 R11: 00000000f49cf6fe R12: ffff880429684700
R13: ffffffff81893f96 R14: ffffffff817d66f0 R15: ffff880427f74200
FS: 0000000000000000(0000) GS:ffff88043fcc0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000072c CR3: 000000041d3df000 CR4: 00000000000006e0
Stack:
ffffffff817b29cf ffff880429684700 ffff88043fcc3e18 ffffffff817b42c2
ffff880429684700 ffff88043fcc3e40 ffffffff817b4332 ffff880429684700
ffff880427f74238 ffff880427f74228 ffff88043fcc3e58 ffffffff81893f96
Call Trace:
<IRQ> [16240.336345] [<ffffffff817b29cf>] ? skb_release_head_state+0x4f/0xb0
[<ffffffff817b42c2>] skb_release_all+0x12/0x30
[<ffffffff817b4332>] kfree_skb+0x32/0x90
[<ffffffff81893f96>] ndisc_error_report+0x36/0x40
[<ffffffff817d4de1>] neigh_invalidate+0x81/0xf0
[<ffffffff817d68f7>] neigh_timer_handler+0x207/0x2b0
[<ffffffff81109295>] call_timer_fn+0x35/0x120
[<ffffffff81109db7>] run_timer_softirq+0x1d7/0x460
[<ffffffff8106155e>] ? kvm_sched_clock_read+0x1e/0x30
[<ffffffff810366b9>] ? sched_clock+0x9/0x10
[<ffffffff810cfed2>] ? sched_clock_cpu+0x72/0xa0
[<ffffffff818dd537>] __do_softirq+0xd7/0x289
[<ffffffff810a6c95>] irq_exit+0xb5/0xc0
[<ffffffff818dd372>] smp_apic_timer_interrupt+0x42/0x50
[<ffffffff818dc682>] apic_timer_interrupt+0x82/0x90
<EOI> [16240.395776] [<ffffffff818da156>] ? native_safe_halt+0x6/0x10
[<ffffffff818d9e6e>] default_idle+0x1e/0xd0
[<ffffffff8103797f>] arch_cpu_idle+0xf/0x20
[<ffffffff818da2c5>] default_idle_call+0x35/0x40
[<ffffffff810e3eb5>] cpu_startup_entry+0x185/0x210
[<ffffffff81050433>] start_secondary+0x103/0x130
RIP [<ffffffffa05df765>] rxe_skb_tx_dtor+0x15/0x50 [rdma_rxe]
Fixes: 8700e3e7c485 ("Soft RoCE driver")
Signed-off-by: Yonatan Cohen <yonatanc@xxxxxxxxxxxx>
Reviewed-by: Moni Shoua <monis@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
---
drivers/infiniband/sw/rxe/rxe_net.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
index c3a140ed4df2..08f3f90d2912 100644
--- a/drivers/infiniband/sw/rxe/rxe_net.c
+++ b/drivers/infiniband/sw/rxe/rxe_net.c
@@ -441,6 +441,8 @@ static void rxe_skb_tx_dtor(struct sk_buff *skb)
if (unlikely(qp->need_req_skb &&
skb_out < RXE_INFLIGHT_SKBS_PER_QP_LOW))
rxe_run_task(&qp->req.task, 1);
+
+ rxe_drop_ref(qp);
}
int rxe_send(struct rxe_dev *rxe, struct rxe_pkt_info *pkt, struct sk_buff *skb)
@@ -473,6 +475,7 @@ int rxe_send(struct rxe_dev *rxe, struct rxe_pkt_info *pkt, struct sk_buff *skb)
return -EAGAIN;
}
+ rxe_add_ref(pkt->qp);
atomic_inc(&pkt->qp->skb_out);
kfree_skb(skb);
--
2.13.1
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