4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit 2c1ec6fda2d07044cda922ee25337cf5d4b429b3 upstream.
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)); }
Fixes: ee7fb331c3ac ("libata: add support for NCQ commands for SG interface") Reported-by: syzbot+2f69ca28df61bdfc77cd36af2e789850355a221e@syzkaller.appspotmail.com Cc: stable@vger.kernel.org # v4.4+ Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/ata/libata-scsi.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3226,6 +3226,12 @@ static unsigned int ata_scsi_pass_thru(s 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;