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Mikulas Patocka
897d9006e7
[ Upstream commitd9f3e47d3f] There are two problems with the recursive correction: 1. It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state. 2. It doesn't work. In fec_read_bufs we store data into the variable "fio->bufs", but fio bufs is shared between recursive invocations, if "verity_hash_for_block" invoked correction recursively, it would overwrite partially filled fio->bufs. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reported-by: Guangwu Zhang <guazhang@redhat.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Eric Biggers <ebiggers@kernel.org> [ The context change is due to the commitbdf253d580("dm-verity: remove support for asynchronous hashes") in v6.18 and the commit9356fcfe0a("dm verity: set DM_TARGET_SINGLETON feature flag") in v6.9 which are irrelevant to the logic of this patch. ] Signed-off-by: Rahul Sharma <black.hawk@163.com> 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.