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commit 2da376228a2427501feb9d15815a45dbdbdd753e upstream. Syzbot found an issue [1] in ext4_fallocate(). The C reproducer [2] calls fallocate(), passing size 0xffeffeff000ul, and offset 0x1000000ul, which, when added together exceed the bitmap_maxbytes for the inode. This triggers a BUG in ext4_ind_remove_space(). According to the comments in this function the 'end' parameter needs to be one block after the last block to be removed. In the case when the BUG is triggered it points to the last block. Modify the ext4_punch_hole() function and add constraint that caps the length to satisfy the one before laster block requirement. LINK: [1] https://syzkaller.appspot.com/bug?id=b80bd9cf348aac724a4f4dff251800106d721331 LINK: [2] https://syzkaller.appspot.com/text?tag=ReproC&x=14ba0238700000 Fixes: a4bb6b64e39a ("ext4: enable "punch hole" functionality") Reported-by: syzbot+7a806094edd5d07ba029@syzkaller.appspotmail.com Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org> Link: https://lore.kernel.org/r/20220331200515.153214-1-tadeusz.struk@linaro.org Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org 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.