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commitcd68c48ea1upstream. When reading unformatted tracks on ESE devices, the corresponding memory areas are simply set to zero for each segment. This is done incorrectly for blocksizes < 4096. There are two problems. First, the increment of dst is done using the counter of the loop (off), which is increased by blksize every iteration. This leads to a much bigger increment for dst as actually intended. Second, the increment of dst is done before the memory area is set to 0, skipping a significant amount of bytes of memory. This leads to illegal overwriting of memory and ultimately to a kernel panic. This is not a problem with 4k blocksize because blk_queue_max_segment_size is set to PAGE_SIZE, always resulting in a single iteration for the inner segment loop (bv.bv_len == blksize). The incorrectly used 'off' value to increment dst is 0 and the correct memory area is used. In order to fix this for blksize < 4k, increment dst correctly using the blksize and only do it at the end of the loop. Fixes:5e2b17e712("s390/dasd: Add dynamic formatting support for ESE volumes") Cc: stable@vger.kernel.org # v5.3+ Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com> Reviewed-by: Stefan Haberland <sth@linux.ibm.com> Link: https://lore.kernel.org/r/20220505141733.1989450-4-sth@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.