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commit 11509910c599cbd04585ec35a6d5e1a0053d84c1 upstream. In jfs_dmap.c at line 381, BLKTODMAP is used to get a logical block number inside dbFree(). db_l2nbperpage, which is the log2 number of blocks per page, is passed as an argument to BLKTODMAP which uses it for shifting. Syzbot reported a shift out-of-bounds crash because db_l2nbperpage is too big. This happens because the large value is set without any validation in dbMount() at line 181. Thus, make sure that db_l2nbperpage is correct while mounting. Max number of blocks per page = Page size / Min block size => log2(Max num_block per page) = log2(Page size / Min block size) = log2(Page size) - log2(Min block size) => Max db_l2nbperpage = L2PSIZE - L2MINBLOCKSIZE Reported-and-tested-by: syzbot+d2cd27dcf8e04b232eb2@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?id=2a70a453331db32ed491f5cbb07e81bf2d225715 Cc: stable@vger.kernel.org Suggested-by: Dave Kleikamp <dave.kleikamp@oracle.com> Signed-off-by: Siddh Raman Pant <code@siddh.me> Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.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.