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Yuezhang Mo
d141e72aef
exfat: fix the new buffer was not zeroed before writing
In exfat, not only the newly allocated space will be mapped as the new buffer, but also the space between ->valid_size and the file size will be mapped as the new buffer. If the buffer is mapped as new in ->write_begin(), it will be zeroed. But if the buffer has been mapped as new before ->write_begin(), ->write_begin() will not zero them, resulting in access to uninitialized data. So this commit uses folio_zero_new_buffers() to zero the new buffers after ->write_begin(). Fixes: 6630ea49103c ("exfat: move extend valid_size into ->page_mkwrite()") Reported-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=91ae49e1c1a2634d20c0 Tested-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com> Signed-off-by: Namjae Jeon <linkinjeon@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 reStructuredText 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.
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