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scsi: vmw_pscsi: Fix use-after-free in pvscsi_queue_lck()

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Once we unlock adapter->hw_lock in pvscsi_queue_lck() nothing prevents just
queued scsi_cmnd from completing and freeing the request. Thus cmd->cmnd[0]
dereference can dereference already freed request leading to kernel crashes
or other issues (which one of our customers observed). Store cmd->cmnd[0]
in a local variable before unlocking adapter->hw_lock to fix the issue.

CC: <stable@vger.kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Jan Kara 2019-06-19 09:05:41 +02:00 committed by Martin K. Petersen
parent 5589b08e5b
commit 240b4cc8fd
1 changed files with 4 additions and 2 deletions
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6
drivers/scsi/vmw_pvscsi.c
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@ -763,6 +763,7 @@ static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd
struct pvscsi_adapter *adapter = shost_priv(host);
struct pvscsi_ctx *ctx;
unsigned long flags;
unsigned char op;
spin_lock_irqsave(&adapter->hw_lock, flags);
@ -775,13 +776,14 @@ static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd
}
cmd->scsi_done = done;
op = cmd->cmnd[0];
dev_dbg(&cmd->device->sdev_gendev,
"queued cmd %p, ctx %p, op=%x\n", cmd, ctx, cmd->cmnd[0]);
"queued cmd %p, ctx %p, op=%x\n", cmd, ctx, op);
spin_unlock_irqrestore(&adapter->hw_lock, flags);
pvscsi_kick_io(adapter, cmd->cmnd[0]);
pvscsi_kick_io(adapter, op);
return 0;
}