| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.11 106/114] libata: reject passthrough WRITE SAME requests | Date | Thu, 18 May 2017 12:46:56 +0200 |
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4.11-stable review patch. If anyone has any objections, please let me know.
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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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