[PATCH AUTOSEL 5.7 022/388] scsi: core: free sgtables in case command setup fails

Sasha Levin
2020-06-18T02:51:59Z

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

[ Upstream commit 20a66f2bf280277ab5bb22e27445153b4eb0ac88 ]

In case scsi_setup_fs_cmnd() fails we're not freeing the sgtables allocated
by scsi_init_io(), thus we leak the allocated memory.

Free the sgtables allocated by scsi_init_io() in case scsi_setup_fs_cmnd()
fails.

Technically scsi_setup_scsi_cmnd() does not suffer from this problem as it
can only fail if scsi_init_io() fails, so it does not have sgtables
allocated. But to maintain symmetry and as a measure of defensive
programming, free the sgtables on scsi_setup_scsi_cmnd() failure as well.
scsi_mq_free_sgtables() has safeguards against double-freeing of memory so
this is safe to do.

While we're at it, rename scsi_mq_free_sgtables() to scsi_free_sgtables().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=205595
Link: https://lore.kernel.org/r/20200428104605.8143-2-johannes.thumshirn@wdc.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/scsi_lib.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 06c260f6cdae..3ecdae18597d 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -548,7 +548,7 @@ static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
}
}

-static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
+static void scsi_free_sgtables(struct scsi_cmnd *cmd)
{
if (cmd->sdb.table.nents)
sg_free_table_chained(&cmd->sdb.table,
@@ -560,7 +560,7 @@ static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)

static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
{
- scsi_mq_free_sgtables(cmd);
+ scsi_free_sgtables(cmd);
scsi_uninit_cmd(cmd);
}

@@ -1059,7 +1059,7 @@ blk_status_t scsi_init_io(struct scsi_cmnd *cmd)

return BLK_STS_OK;
out_free_sgtables:
- scsi_mq_free_sgtables(cmd);
+ scsi_free_sgtables(cmd);
return ret;
}
EXPORT_SYMBOL(scsi_init_io);
@@ -1190,6 +1190,7 @@ static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
struct request *req)
{
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
+ blk_status_t ret;

if (!blk_rq_bytes(req))
cmd->sc_data_direction = DMA_NONE;
@@ -1199,9 +1200,14 @@ static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
cmd->sc_data_direction = DMA_FROM_DEVICE;

if (blk_rq_is_scsi(req))
- return scsi_setup_scsi_cmnd(sdev, req);
+ ret = scsi_setup_scsi_cmnd(sdev, req);
else
- return scsi_setup_fs_cmnd(sdev, req);
+ ret = scsi_setup_fs_cmnd(sdev, req);
+
+ if (ret != BLK_STS_OK)
+ scsi_free_sgtables(cmd);
+
+ return ret;
}

static blk_status_t
--
2.25.1