From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: [PATCH v2 2/8] IB/srp: Avoid that duplicate responses trigger a kernel bug Date: Tue, 14 Feb 2017 10:56:30 -0800 Message-ID: <20170214185636.29250-3-bart.vanassche@sandisk.com> References: <20170214185636.29250-1-bart.vanassche@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20170214185636.29250-1-bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Ledford Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Bart Van Assche , Israel Rukshin , Max Gurtovoy , Laurence Oberman , Steve Feeley , stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org After srp_process_rsp() returns there is a short time during which the scsi_host_find_tag() call will return a pointer to the SCSI command that is being completed. If during that time a duplicate response is received, avoid that the following call stack appears: BUG: unable to handle kernel NULL pointer dereference at (null) IP: srp_recv_done+0x450/0x6b0 [ib_srp] Oops: 0000 [#1] SMP CPU: 10 PID: 0 Comm: swapper/10 Not tainted 4.10.0-rc7-dbg+ #1 Call Trace: __ib_process_cq+0x4b/0xd0 [ib_core] ib_poll_handler+0x1d/0x70 [ib_core] irq_poll_softirq+0xba/0x120 __do_softirq+0xba/0x4c0 irq_exit+0xbe/0xd0 smp_apic_timer_interrupt+0x38/0x50 apic_timer_interrupt+0x90/0xa0 RIP: srp_recv_done+0x450/0x6b0 [ib_srp] RSP: ffff88046f483e20 Signed-off-by: Bart Van Assche Cc: Israel Rukshin Cc: Max Gurtovoy Cc: Laurence Oberman Cc: Steve Feeley Cc: --- drivers/infiniband/ulp/srp/ib_srp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index 07e3613e4798..12027e3a4dec 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -1892,9 +1892,11 @@ static void srp_process_rsp(struct srp_rdma_ch *ch, struct srp_rsp *rsp) complete(&ch->tsk_mgmt_done); } else { scmnd = scsi_host_find_tag(target->scsi_host, rsp->tag); - if (scmnd) { + if (scmnd && scmnd->host_scribble) { req = (void *)scmnd->host_scribble; scmnd = srp_claim_req(ch, req, NULL, scmnd); + } else { + scmnd = NULL; } if (!scmnd) { shost_printk(KERN_ERR, target->scsi_host, -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html