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authorEric Biggers <ebiggers@google.com>2018-02-03 20:33:51 -0800
committerTejun Heo <tj@kernel.org>2018-02-12 09:21:25 -0800
commit2c1ec6fda2d07044cda922ee25337cf5d4b429b3 (patch)
tree330a6dd0e7e41e36f7504d3385999aa75bee1dd2 /drivers/ata
parent9173e5e80729c8434b8d27531527c5245f4a5594 (diff)
downloadlinux-2c1ec6fda2d07044cda922ee25337cf5d4b429b3.tar.bz2
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)); } 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>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/libata-scsi.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 9ae8986bae48..89a9d4a2efc8 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -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;