| Message ID | 20221014000056.176658-1-john.cabaj@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | [SRU,Bionic,1/1] (upstream) video: fbdev: i740fb: Error out if 'pixclock' equals zero | expand |
On 14.10.22 02:00, John Cabaj wrote: > From: Zheyu Ma <zheyuma97@gmail.com> > > CVE-2022-3061 > > The userspace program could pass any values to the driver through > ioctl() interface. If the driver doesn't check the value of 'pixclock', > it may cause divide error. > > Fix this by checking whether 'pixclock' is zero in the function > i740fb_check_var(). > > The following log reveals it: > > divide error: 0000 [#1] PREEMPT SMP KASAN PTI > RIP: 0010:i740fb_decode_var drivers/video/fbdev/i740fb.c:444 [inline] > RIP: 0010:i740fb_set_par+0x272f/0x3bb0 drivers/video/fbdev/i740fb.c:739 > Call Trace: > fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1036 > do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1112 > fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1191 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:874 [inline] > > Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> > Signed-off-by: Helge Deller <deller@gmx.de> > (cherry picked from commit 15cf0b82271b1823fb02ab8c377badba614d95d5) > Signed-off-by: John Cabaj <john.cabaj@canonical.com> > --- > drivers/video/fbdev/i740fb.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c > index 4147a9534179..e7e0445b0808 100644 > --- a/drivers/video/fbdev/i740fb.c > +++ b/drivers/video/fbdev/i740fb.c > @@ -660,6 +660,9 @@ static int i740fb_decode_var(const struct fb_var_screeninfo *var, > > static int i740fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) > { > + if (!var->pixclock) > + return -EINVAL; > + > switch (var->bits_per_pixel) { > case 8: > var->red.offset = var->green.offset = var->blue.offset = 0;
diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c index 4147a9534179..e7e0445b0808 100644 --- a/drivers/video/fbdev/i740fb.c +++ b/drivers/video/fbdev/i740fb.c @@ -660,6 +660,9 @@ static int i740fb_decode_var(const struct fb_var_screeninfo *var, static int i740fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) { + if (!var->pixclock) + return -EINVAL; + switch (var->bits_per_pixel) { case 8: var->red.offset = var->green.offset = var->blue.offset = 0;