0d0bd28c50
r5l_flush_stripe_to_raid() will check if the list 'flushing_ios' is
empty, and then submit 'flush_bio', however, r5l_log_flush_endio()
is clearing the list first and then clear the bio, which will cause
null-ptr-deref:
T1: submit flush io
raid5d
handle_active_stripes
r5l_flush_stripe_to_raid
// list is empty
// add 'io_end_ios' to the list
bio_init
submit_bio
// io1
T2: io1 is done
r5l_log_flush_endio
list_splice_tail_init
// clear the list
T3: submit new flush io
...
r5l_flush_stripe_to_raid
// list is empty
// add 'io_end_ios' to the list
bio_init
bio_uninit
// clear bio->bi_blkg
submit_bio
// null-ptr-deref
Fix this problem by clearing bio before clearing the list in
r5l_log_flush_endio().
Fixes: 0dd00cba99c3 ("raid5-cache: fully initialize flush_bio when needed")
Reported-and-tested-by: Corey Hickey <bugfood-ml@fatooh.org>
Closes: https://lore.kernel.org/all/cddd7213-3dfd-4ab7-a3ac-edd54d74a626@fatooh.org/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.