4.11-stable review patch. If anyone has any objections, please let me know.
------------------ From: Christoph Hellwig <[email protected]> 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 <[email protected]> Reviewed-by: Martin K. Petersen <[email protected]> Signed-off-by: Tejun Heo <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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;
