Bug 1734246 (CVE-2019-14284) - CVE-2019-14284 kernel: denial of service in drivers/block/floppy.c by setup_format_params division-by-zero
Summary: CVE-2019-14284 kernel: denial of service in drivers/block/floppy.c by setup_f...
Keywords:
Status: CLOSED WONTFIX
Alias: CVE-2019-14284
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1734250 1735597 1735598 1735599 1735600 1735601 1735602
Blocks: 1734249
TreeView+ depends on / blocked
 
Reported: 2019-07-30 04:52 UTC by Dhananjay Arunesh
Modified: 2021-02-16 21:36 UTC (History)
46 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in the Linux kernel’s floppy disk driver implementation. A local attacker with access to the floppy disk device file (/dev/fd0 through to /dev/fdN) can create a situation that causes the kernel to divide by zero. This requires two consecutive ioctl calls to be issued. The first ioctl call sets the sector and rate values, and the second ioctl is the call to format the floppy disk to the appropriate values. This flaw can cause the system to divide by zero and panic the host. No media (floppy) is required to be inserted for this attack to work properly.
Clone Of:
Environment:
Last Closed: 2020-01-14 22:31:56 UTC


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Description Dhananjay Arunesh 2019-07-30 04:52:46 UTC
A vulnerability was found in the Linux kernels floppy driver implementation.  A local attacker with access to the floppy disk device file (/dev/fd0 through to /dev/fdN) can create a situation which can convince the kernel to divide by zero.  It requires two consecutive ioctls to be issued the first to set the sector and rate values, the second would be the call to format the floppy disk to the appropriate values.  This can cause the system to divide by zero and panic the host.  No media (floppy) is required to be inserted for this attack to work correctly.


Systems using QEMU will likely have the virtual floppy disk controller (FDC) enabled by default, Linux guests using this configuration will auto-load the floppy kernel module and likely be affected.




External References:
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.2.3

Upstream commit:
https://github.com/torvalds/linux/commit/f3554aeb991214cbfafd17d55e2bfddb50282e32
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f3554aeb991214cbfafd17d55e2bfddb50282e32

Comment 1 Dhananjay Arunesh 2019-07-30 04:56:58 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1734250]

Comment 2 Justin M. Forbes 2019-07-30 14:08:07 UTC
This was fixed for Fedora with the 5.1.20 stable kernel update.

Comment 3 Wade Mealing 2019-08-01 06:09:09 UTC
Mitigation:

The kernel module named 'floppy' contains the affected code, this can be blacklisted using the standard blacklisting techniques or disabled in the systems BIOS.  See https://access.redhat.com/solutions/41278 for how to blacklist a kernel module.

Virtualized guest systems can also remove the system from the guests configuration to ensure that the module does not load.


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