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Zheyu Ma a249e1b89c video: fbdev: arkfb: Fix a divide-by-zero bug in ark_set_pixclock()
[ Upstream commit 2f1c4523f7a3aaabe7e53d3ebd378292947e95c8 ]

Since the user can control the arguments of the ioctl() from the user
space, under special arguments that may result in a divide-by-zero bug
in:
  drivers/video/fbdev/arkfb.c:784: ark_set_pixclock(info, (hdiv * info->var.pixclock) / hmul);
with hdiv=1, pixclock=1 and hmul=2 you end up with (1*1)/2 = (int) 0.
and then in:
  drivers/video/fbdev/arkfb.c:504: rv = dac_set_freq(par->dac, 0, 1000000000 / pixclock);
we'll get a division-by-zero.

The following log can reveal it:

divide error: 0000 [#1] PREEMPT SMP KASAN PTI
RIP: 0010:ark_set_pixclock drivers/video/fbdev/arkfb.c:504 [inline]
RIP: 0010:arkfb_set_par+0x10fc/0x24c0 drivers/video/fbdev/arkfb.c:784
Call Trace:
 fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1034
 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110
 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189

Fix this by checking the argument of ark_set_pixclock() first.

Fixes: 681e14730c ("arkfb: new framebuffer driver for ARK Logic cards")
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-08-25 11:18:08 +02:00
arch x86/numa: Use cpumask_available instead of hardcoded NULL check 2022-08-25 11:18:08 +02:00
block blk-mq: don't create hctx debugfs dir until q->debugfs_dir is created 2022-08-25 11:17:36 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:11:22 +02:00
crypto crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-22 14:11:18 +02:00
Documentation x86: Handle idle=nomwait cmdline properly for x86_idle 2022-08-25 11:17:28 +02:00
drivers video: fbdev: arkfb: Fix a divide-by-zero bug in ark_set_pixclock() 2022-08-25 11:18:08 +02:00
fs fuse: Remove the control interface for virtio-fs 2022-08-25 11:18:05 +02:00
include mfd: t7l66xb: Drop platform disable callback 2022-08-25 11:18:04 +02:00
init random: handle latent entropy and command line from random_init() 2022-06-22 14:11:17 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-14 18:11:41 +02:00
kernel kprobes: Forbid probing on trampoline and BPF code areas 2022-08-25 11:18:07 +02:00
lib locking/refcount: Consolidate implementations of refcount_t 2022-07-29 17:14:17 +02:00
LICENSES
mm mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region 2022-08-25 11:17:58 +02:00
net dccp: put dccp_qpolicy_full() and dccp_qpolicy_push() in the same lock 2022-08-25 11:17:49 +02:00
samples
scripts scripts/faddr2line: Fix vmlinux detection on arm64 2022-08-25 11:18:08 +02:00
security selinux: Add boundary check in put_entry() 2022-08-25 11:17:32 +02:00
sound ASoC: audio-graph-card: Add of_node_put() in fail path 2022-08-25 11:18:05 +02:00
tools genelf: Use HAVE_LIBCRYPTO_SUPPORT, not the never defined HAVE_LIBCRYPTO 2022-08-25 11:18:08 +02:00
usr
virt KVM: Don't null dereference ops->destroy 2022-08-11 12:57:52 +02:00
.clang-format
.cocciconfig
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MAINTAINERS MAINTAINERS: co-maintain random.c 2022-06-22 14:11:05 +02:00
Makefile Makefile: link with -z noexecstack --no-warn-rwx-segments 2022-08-25 11:17:17 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.