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libata: reject passthrough WRITE SAME requests

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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>
Cc: stable@vger.kernel.org
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Christoph Hellwig 2017-04-25 13:39:54 +02:00 committed by Tejun Heo
parent 1a92e99a55
commit c6ade20f5e
1 changed files with 8 additions and 0 deletions
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8
drivers/ata/libata-scsi.c
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@ -3462,6 +3462,14 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
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;