FAILED: patch "[PATCH] libata: don't try to pass through NCQ commands to non-NCQ" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Eric Biggers <[email protected]>
Date: Sat, 3 Feb 2018 20:33:51 -0800
Subject: [PATCH] libata: don't try to pass through NCQ commands to non-NCQ
devices

syzkaller hit a WARN() in ata_bmdma_qc_issue() when writing to /dev/sg0. This happened because it issued an ATA pass-through command (ATA_16) where the protocol field indicated that NCQ should be used -- but the device did not support NCQ.

We could just remove the WARN() from libata-sff.c, but the real problem seems to be that the SCSI -> ATA translation code passes through NCQ commands without verifying that the device actually supports NCQ.

Fix this by adding the appropriate check to ata_scsi_pass_thru().

Here's reproducer that works in QEMU when /dev/sg0 refers to a disk of the default type ("82371SB PIIX3 IDE"):

    #include <fcntl.h>
    #include <unistd.h>

    int main()
    {
            char buf[53] = { 0 };

	    buf[36] = 0x85;		/* ATA_16 */
	    buf[37] = (12 << 1);	/* FPDMA */
	    buf[38] = 0x1;		/* Has data */
	    buf[51] = 0xC8;		/* ATA_CMD_READ */
            write(open("/dev/sg0", O_RDWR), buf, sizeof(buf));
    }

index 9ae8986bae48..89a9d4a2efc8 100644
@@ -3316,6 +3316,12 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
 		goto invalid_fld;
 	}
 
+	/* We may not issue NCQ commands to devices not supporting NCQ */
+	if (ata_is_ncq(tf->protocol) && !ata_ncq_enabled(dev)) {
+		fp = 1;
+		goto invalid_fld;
+	}
+
 	/* sanity check for pio multi commands */
 	if ((cdb[1] & 0xe0) && !is_multi_taskfile(tf)) {
 		fp = 1;