From 6f58c780e5a5b43a6d2121e0d43cdcba1d3cc5fc Mon Sep 17 00:00:00 2001 From: "Dr. Greg Wettstein" Date: Mon, 24 Feb 2014 13:59:53 -0600 Subject: [PATCH] qla2xxx: Fix kernel panic on selective retransmission request A selective retransmission request (SRR) is a fibre-channel protocol control request which provides support for requesting retransmission of a data sequence in response to an issue such as frame loss or corruption. These events are experienced infrequently in fibre-channel based networks which makes it difficult to test and assess codepaths which handle these events. We were fortunate enough, for some definition of fortunate, to have a metro-area single-mode SAN link which, at 10 GBPS sustained load levels, would consistently generate SRR's in a SCST based target implementation using our SCST/in-kernel Qlogic target interface driver. In response to an SRR the in-kernel Qlogic target driver immediately panics resulting in a catastrophic storage failure for serviced initiators. The culprit was a debug statement in the qla_target.c file which does not verify that a pointer to the SCSI CDB is not null. The unchecked pointer dereference results in the kernel panic and resultant system failure. The other two references to the SCSI CDB by the SRR handling code use a ternary operator to verify a non-null pointer is being acted on. This patch simply adds a similar test to the implicated debug statement. This patch is a candidate for any stable kernel being maintained since it addresses a potentially catastrophic event with minimal downside. Signed-off-by: Dr. Greg Wettstein Cc: #3.5+ Signed-off-by: Nicholas Bellinger --- drivers/scsi/qla2xxx/qla_target.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c index f2e1c5a5fdbb..0cb73074c199 100644 --- a/drivers/scsi/qla2xxx/qla_target.c +++ b/drivers/scsi/qla2xxx/qla_target.c @@ -3202,7 +3202,8 @@ static void qlt_handle_srr_work(struct work_struct *work) ql_dbg(ql_dbg_tgt_mgt, vha, 0xf02c, "SRR cmd %p (se_cmd %p, tag %d, op %x), " "sg_cnt=%d, offset=%d", cmd, &cmd->se_cmd, cmd->tag, - se_cmd->t_task_cdb[0], cmd->sg_cnt, cmd->offset); + se_cmd->t_task_cdb ? se_cmd->t_task_cdb[0] : 0, + cmd->sg_cnt, cmd->offset); qlt_handle_srr(vha, sctio, imm);