[PATCH 01/33] scsi: qla2xxx: Clamp MSI-X derived queue counts to avoid truncation

ha->msix_count is u16, but ha->max_req_queues, ha->max_rsp_queues and
ha->max_qpairs are u8. Deriving the queue count as
"ha->max_req_queues = ha->msix_count - 1" therefore truncates: a board
(or a misconfigured/malicious hot-plugged device) advertising 257 MSI-X
vectors yields msix_count - 1 == 256, which truncates to 0. An MSI-X
count of 1 zeroes it as well, and in target mode the subsequent
"ha->max_req_queues--" then underflows 0 to 255.

When the count is 0, qla2x00_alloc_queues() calls
kzalloc_objs(struct req_que *, 0), which returns ZERO_SIZE_PTR. That is
not NULL, so the allocation check passes and the following
"ha->req_q_map[0] = req" dereferences ZERO_SIZE_PTR, corrupting memory
or crashing the kernel.

Add qla_calc_queue_count() to clamp the derived value into
[1, QLA_MAX_QUEUES - 1] so it always fits in u8 and is never zero, and
use it at all three derivation sites (qla25xx_iospace_config(),
qla83xx_iospace_config() and qla24xx_enable_msix()). Also guard the
target-mode decrement so it cannot reintroduce a zero (which would in
turn underflow max_qpairs).

Fixes: d74595278f4a ("scsi: qla2xxx: Add multiple queue pair functionality.")
Cc: [email protected]
Reported-by: Sashiko <[email protected]>
Signed-off-by: Nilesh Javali <[email protected]>
---
 drivers/scsi/qla2xxx/qla_inline.h | 13 +++++++++++++
 drivers/scsi/qla2xxx/qla_isr.c    |  4 ++--
 drivers/scsi/qla2xxx/qla_os.c     |  6 +++---
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_inline.h b/drivers/scsi/qla2xxx/qla_inline.h
index 9e33bcc87b39..90da4bad8e6e 100644
--- a/drivers/scsi/qla2xxx/qla_inline.h
+++ b/drivers/scsi/qla2xxx/qla_inline.h
@@ -138,6 +138,19 @@ qla_logio_set_vp_index(struct qla_hw_data *ha, void *pkt, u16 vp_idx)
 		((struct logio_entry_24xx *)pkt)->vp_index = vp_idx;
 }
 
+static inline u8
+qla_calc_queue_count(u16 msix_count)
+{
+	/*
+	 * Request/response queues are bounded by the MSI-X vector count less
+	 * the mailbox vector.  These counters are u8, so a board advertising
+	 * e.g. 257 vectors would truncate msix_count - 1 (256) to 0 and hand
+	 * kzalloc_objs() a zero count (ZERO_SIZE_PTR), faulting on the first
+	 * ha->req_q_map[0] store.  Clamp into [1, QLA_MAX_QUEUES - 1].
+	 */
+	return clamp_t(u16, msix_count - 1, 1, QLA_MAX_QUEUES - 1);
+}
+
 static inline void
 qla2x00_poll(struct rsp_que *rsp)
 {
diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
index 9d2d11f10a76..86e1e8428f2a 100644
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -4705,10 +4705,10 @@ qla24xx_enable_msix(struct qla_hw_data *ha, struct rsp_que *rsp)
 		ha->msix_count = ret;
 		/* Recalculate queue values */
 		if (ha->mqiobase && (ql2xmqsupport || ql2xnvmeenable)) {
-			ha->max_req_queues = ha->msix_count - 1;
+			ha->max_req_queues = qla_calc_queue_count(ha->msix_count);
 
 			/* ATIOQ needs 1 vector. That's 1 less QPair */
-			if (QLA_TGT_MODE_ENABLED())
+			if (QLA_TGT_MODE_ENABLED() && ha->max_req_queues > 1)
 				ha->max_req_queues--;
 
 			ha->max_rsp_queues = ha->max_req_queues;
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 186c6c7a3944..5209dda45459 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -2132,7 +2132,7 @@ qla2x00_iospace_config(struct qla_hw_data *ha)
 		ha->msix_count = msix + 1;
 		/* Max queues are bounded by available msix vectors */
 		/* MB interrupt uses 1 vector */
-		ha->max_req_queues = ha->msix_count - 1;
+		ha->max_req_queues = qla_calc_queue_count(ha->msix_count);
 		ha->max_rsp_queues = ha->max_req_queues;
 		/* Queue pairs is the max value minus the base queue pair */
 		ha->max_qpairs = ha->max_rsp_queues - 1;
@@ -2224,10 +2224,10 @@ qla83xx_iospace_config(struct qla_hw_data *ha)
 		 */
 		if (ql2xmqsupport || ql2xnvmeenable) {
 			/* MB interrupt uses 1 vector */
-			ha->max_req_queues = ha->msix_count - 1;
+			ha->max_req_queues = qla_calc_queue_count(ha->msix_count);
 
 			/* ATIOQ needs 1 vector. That's 1 less QPair */
-			if (QLA_TGT_MODE_ENABLED())
+			if (QLA_TGT_MODE_ENABLED() && ha->max_req_queues > 1)
 				ha->max_req_queues--;
 
 			ha->max_rsp_queues = ha->max_req_queues;
-- 
2.47.3