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commit2c1ec6fda2upstream. 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:ee7fb331c3("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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.