From 0256d09d99efebbf83f115d19a10ae7a7668dfd9 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 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 Reviewed-by: Martin K. Petersen Signed-off-by: Tejun Heo [bwh: Backported to 3.16: - Open-code blk_rq_is_passthrough() - We don't distinguish which field is invaid so goto invalid_fld - Adjust context] Signed-off-by: Ben Hutchings --- 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 b87512ff6292..90112092d1e6 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3097,6 +3097,14 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc) if (unlikely(!dev->dma_mode)) 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)) goto invalid_fld; scsi_16_lba_len(cdb, &block, &n_block);