[PATCH 3.18 084/183] scsi: fix random memory corruption with scsi-mq + T10 PI

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>

commit 120bb3e1e36da9c1ae6b978c825a28b944a5d7c5 upstream.

This fixes random memory corruption triggered when all three of the
following are true:

* scsi-mq enabled
* T10 Protection Information (DIF) enabled
* SCSI host with sg_tablesize > SCSI_MAX_SG_SEGMENTS (128)

The symptoms of this bug are unpredictable memory corruption, BUG()s,
oopses, lockups, etc., any of which may appear to be completely
unrelated to the root cause.

Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
Reviewed-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/scsi/scsi_lib.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1829,7 +1829,9 @@ static int scsi_mq_prep_fn(struct reques
 
 	if (scsi_host_get_prot(shost)) {
 		cmd->prot_sdb = (void *)sg +
-			shost->sg_tablesize * sizeof(struct scatterlist);
+			min_t(unsigned int,
+			      shost->sg_tablesize, SCSI_MAX_SG_SEGMENTS) *
+			sizeof(struct scatterlist);
 		memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
 
 		cmd->prot_sdb->table.sgl =


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