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Subject[PATCH 4.11 106/114] libata: reject passthrough WRITE SAME requests
Date
4.11-stable review patch.  If anyone has any objections, please let me know.

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

From: Christoph Hellwig <hch@lst.de>

commit c6ade20f5e50e188d20b711a618b20dd1d50457e upstream.

The WRITE SAME to TRIM translation rewrites the DATA OUT buffer. While
the SCSI code accomodates for this by passing a read-writable buffer
userspace applications don't cater for this behavior. In fact it can
be used to rewrite e.g. a readonly file through mmap and should be
considered as a security fix.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/ata/libata-scsi.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3462,6 +3462,14 @@ static unsigned int ata_scsi_write_same_
if (unlikely(!dev->dma_mode))
goto invalid_opcode;

+ /*
+ * We only allow sending this command through the block layer,
+ * as it modifies the DATA OUT buffer, which would corrupt user
+ * memory for SG_IO commands.
+ */
+ if (unlikely(blk_rq_is_passthrough(scmd->request)))
+ goto invalid_opcode;
+
if (unlikely(scmd->cmd_len < 16)) {
fp = 15;
goto invalid_fld;

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