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@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
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;
--
2.11.0