scsi: core: free sgtables in case command setup fails

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>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 53b9ff12e0306a43f3e70db6ec338d7c8a786d26..01d229ea4e1cab61496b054fe75addf4636c9541 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -531,7 +531,7 @@ 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,
@@ -543,7 +543,7 @@ 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);
 }
 
@@ -1032,7 +1032,7 @@ 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);
@@ -1163,6 +1163,7 @@ 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;
@@ -1172,9 +1173,14 @@ 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