From c6ade20f5e50e188d20b711a618b20dd1d50457e Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 25 Apr 2017 13:39:54 +0200 Subject: [PATCH] libata: reject passthrough WRITE SAME requests 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 Cc: stable@vger.kernel.org Reviewed-by: Martin K. Petersen Signed-off-by: Tejun Heo --- drivers/ata/libata-scsi.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index 1ac70744ae7b..50f56d066936 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -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; -- 2.39.5