a904a690ea
[ Upstream commit f3554aeb991214cbfafd17d55e2bfddb50282e32 ] This fixes a divide by zero error in the setup_format_params function of the floppy driver. Two consecutive ioctls can trigger the bug: The first one should set the drive geometry with such .sect and .rate values for the F_SECT_PER_TRACK to become zero. Next, the floppy format operation should be called. A floppy disk is not required to be inserted. An unprivileged user could trigger the bug if the device is accessible. The patch checks F_SECT_PER_TRACK for a non-zero value in the set_geometry function. The proper check should involve a reasonable upper limit for the .sect and .rate fields, but it could change the UAPI. The patch also checks F_SECT_PER_TRACK in the setup_format_params, and cancels the formatting operation in case of zero. The bug was found by syzkaller. Signed-off-by: Denis Efremov <efremov@ispras.ru> Tested-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.