7fc3b7c298
udf_expand_file_adinicb() calls directly ->writepage to write data expanded into a page. This however misses to setup inode for writeback properly and so we can crash on inode->i_wb dereference when submitting page for IO like: BUG: kernel NULL pointer dereference, address: 0000000000000158 #PF: supervisor read access in kernel mode ... <TASK> __folio_start_writeback+0x2ac/0x350 __block_write_full_page+0x37d/0x490 udf_expand_file_adinicb+0x255/0x400 [udf] udf_file_write_iter+0xbe/0x1b0 [udf] new_sync_write+0x125/0x1c0 vfs_write+0x28e/0x400 Fix the problem by marking the page dirty and going through the standard writeback path to write the page. Strictly speaking we would not even have to write the page but we want to catch e.g. ENOSPC errors early. Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com> CC: stable@vger.kernel.org Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks") Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz>
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.