This is a note to let you know that I've just added the patch titled
libata: remove WARN() for DMA or PIO command without data
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: libata-remove-warn-for-dma-or-pio-command-without-data.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 9173e5e80729c8434b8d27531527c5245f4a5594 Mon Sep 17 00:00:00 2001
From: Eric Biggers ebiggers@google.com Date: Sat, 3 Feb 2018 20:33:27 -0800 Subject: libata: remove WARN() for DMA or PIO command without data
From: Eric Biggers ebiggers@google.com
commit 9173e5e80729c8434b8d27531527c5245f4a5594 upstream.
syzkaller hit a WARN() in ata_qc_issue() when writing to /dev/sg0. This happened because it issued a READ_6 command with no data buffer.
Just remove the WARN(), as it doesn't appear indicate a kernel bug. The expected behavior is to fail the command, which the code does.
Here's a 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[42] = { [36] = 0x8 /* READ_6 */ };
write(open("/dev/sg0", O_RDWR), buf, sizeof(buf)); }
Fixes: f92a26365a72 ("libata: change ATA_QCFLAG_DMAMAP semantics") Reported-by: syzbot+f7b556d1766502a69d85071d2ff08bd87be53d0f@syzkaller.appspotmail.com Cc: stable@vger.kernel.org # v2.6.25+ 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-core.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -5391,8 +5391,7 @@ void ata_qc_issue(struct ata_queued_cmd * We guarantee to LLDs that they will have at least one * non-zero sg if the command is a data command. */ - if (WARN_ON_ONCE(ata_is_data(prot) && - (!qc->sg || !qc->n_elem || !qc->nbytes))) + if (ata_is_data(prot) && (!qc->sg || !qc->n_elem || !qc->nbytes)) goto sys_err;
if (ata_is_dma(prot) || (ata_is_pio(prot) &&
Patches currently in stable-queue which might be from ebiggers@google.com are
queue-4.14/libata-fix-length-validation-of-atapi-relayed-scsi-commands.patch queue-4.14/libata-remove-warn-for-dma-or-pio-command-without-data.patch queue-4.14/libata-don-t-try-to-pass-through-ncq-commands-to-non-ncq-devices.patch