[PATCH v2 12/18] bnx2fc: Fix NULL pointer deref during arm_cq.

Bhanu Prakash Gollapudi
2011-08-05T00:39:16Z

There exists a race condition between CQ doorbell unmap and IO completion path
that arms the CQ which causes a NULL dereference. Protect the ctx_base with
cq_lock to avoid this. Also, wait for the CQ doorbell to be successfully mapped
before arming the CQ.

Also, do not count uncolicited CQ completions for free_sqes.

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
---
drivers/scsi/bnx2fc/bnx2fc_hwi.c | 10 +++++++---
drivers/scsi/bnx2fc/bnx2fc_tgt.c | 19 +++++++++++--------
2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/bnx2fc/bnx2fc_hwi.c b/drivers/scsi/bnx2fc/bnx2fc_hwi.c
index 72cfb14..b241f3d 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_hwi.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_hwi.c
@@ -1009,6 +1009,7 @@ int bnx2fc_process_new_cqes(struct bnx2fc_rport *tgt)
u32 cq_cons;
struct fcoe_cqe *cqe;
u32 num_free_sqes = 0;
+ u32 num_cqes = 0;
u16 wqe;

/*
@@ -1058,10 +1059,11 @@ unlock:
wake_up_process(fps->iothread);
else
bnx2fc_process_cq_compl(tgt, wqe);
+ num_free_sqes++;
}
cqe++;
tgt->cq_cons_idx++;
- num_free_sqes++;
+ num_cqes++;

if (tgt->cq_cons_idx == BNX2FC_CQ_WQES_MAX) {
tgt->cq_cons_idx = 0;
@@ -1070,8 +1072,10 @@ unlock:
1 - tgt->cq_curr_toggle_bit;
}
}
- if (num_free_sqes) {
- bnx2fc_arm_cq(tgt);
+ if (num_cqes) {
+ /* Arm CQ only if doorbell is mapped */
+ if (tgt->ctx_base)
+ bnx2fc_arm_cq(tgt);
atomic_add(num_free_sqes, &tgt->free_sqes);
}
spin_unlock_bh(&tgt->cq_lock);
diff --git a/drivers/scsi/bnx2fc/bnx2fc_tgt.c b/drivers/scsi/bnx2fc/bnx2fc_tgt.c
index 3d28fbe..2f7a7da 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_tgt.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_tgt.c
@@ -133,9 +133,9 @@ retry_ofld:
printk(KERN_ERR PFX "map doorbell failed - no mem\n");
/* upload will take care of cleaning up sess resc */
lport->tt.rport_logoff(rdata);
- }
- /* Arm CQ */
- bnx2fc_arm_cq(tgt);
+ } else
+ /* Arm CQ */
+ bnx2fc_arm_cq(tgt);
return;

ofld_err:
@@ -806,14 +806,14 @@ mem_alloc_failure:
static void bnx2fc_free_session_resc(struct bnx2fc_hba *hba,
struct bnx2fc_rport *tgt)
{
- BNX2FC_TGT_DBG(tgt, "Freeing up session resources\n");
+ void __iomem *ctx_base_ptr;

- if (tgt->ctx_base) {
- iounmap(tgt->ctx_base);
- tgt->ctx_base = NULL;
- }
+ BNX2FC_TGT_DBG(tgt, "Freeing up session resources\n");

spin_lock_bh(&tgt->cq_lock);
+ ctx_base_ptr = tgt->ctx_base;
+ tgt->ctx_base = NULL;
+
/* Free LCQ */
if (tgt->lcq) {
dma_free_coherent(&hba->pcidev->dev, tgt->lcq_mem_size,
@@ -867,4 +867,7 @@ static void bnx2fc_free_session_resc(struct bnx2fc_hba *hba,
tgt->sq = NULL;
}
spin_unlock_bh(&tgt->cq_lock);
+
+ if (ctx_base_ptr)
+ iounmap(ctx_base_ptr);
}
--
1.7.0.6