Commit 4d34a500 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Ben Hutchings

libata: reject passthrough WRITE SAME requests

commit c6ade20f 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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
[bwh: Backported to 3.2:
 - Open-code blk_rq_is_passthrough()
 - We don't distinguish which field is invaid so goto invalid_fld
 - Adjust context]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 258132a3
...@@ -3056,6 +3056,14 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc) ...@@ -3056,6 +3056,14 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
if (unlikely(!dev->dma_mode)) if (unlikely(!dev->dma_mode))
goto invalid_fld; goto invalid_fld;
/*
* 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(scmd->request->cmd_type != REQ_TYPE_FS))
goto invalid_fld;
if (unlikely(scmd->cmd_len < 16)) if (unlikely(scmd->cmd_len < 16))
goto invalid_fld; goto invalid_fld;
scsi_16_lba_len(cdb, &block, &n_block); scsi_16_lba_len(cdb, &block, &n_block);
......
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