| Message ID | 1626235762-2590-1-git-send-email-zheyuma97@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] video: fbdev: kyro: fix a DoS bug by restricting user input | expand |
On Tue, Jul 20, 2021 at 2:50 AM Sam Ravnborg <sam@ravnborg.org> wrote: > > Hi Zheyu, > On Wed, Jul 14, 2021 at 04:09:22AM +0000, Zheyu Ma wrote: > > The user can pass in any value to the driver through the 'ioctl' > > interface. The driver dost not check, which may cause DoS bugs. > > > > The following log reveals it: > > > > divide error: 0000 [#1] PREEMPT SMP KASAN PTI > > RIP: 0010:SetOverlayViewPort+0x133/0x5f0 drivers/video/fbdev/kyro/STG4000OverlayDevice.c:476 > > Call Trace: > > kyro_dev_overlay_viewport_set drivers/video/fbdev/kyro/fbdev.c:378 [inline] > > kyrofb_ioctl+0x2eb/0x330 drivers/video/fbdev/kyro/fbdev.c:603 > > do_fb_ioctl+0x1f3/0x700 drivers/video/fbdev/core/fbmem.c:1171 > > fb_ioctl+0xeb/0x130 drivers/video/fbdev/core/fbmem.c:1185 > > vfs_ioctl fs/ioctl.c:48 [inline] > > __do_sys_ioctl fs/ioctl.c:753 [inline] > > __se_sys_ioctl fs/ioctl.c:739 [inline] > > __x64_sys_ioctl+0x19b/0x220 fs/ioctl.c:739 > > do_syscall_64+0x32/0x80 arch/x86/entry/common.c:46 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > > Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> > > --- > > Changes in v2: > > - Validate the inputs on a higher level > > Much better, thanks. > When a line is continued like here the statement shall aling with the > opening brace. I fixed it up when applying the patch to drm-misc-next so > no need to do anything this time. Thanks for your kind reminder, I will pay attention next time. Regards, Zheyu Ma
diff --git a/drivers/video/fbdev/kyro/fbdev.c b/drivers/video/fbdev/kyro/fbdev.c index 8fbde92ae8b9..eb0cbd1d12d5 100644 --- a/drivers/video/fbdev/kyro/fbdev.c +++ b/drivers/video/fbdev/kyro/fbdev.c @@ -372,6 +372,11 @@ static int kyro_dev_overlay_viewport_set(u32 x, u32 y, u32 ulWidth, u32 ulHeight /* probably haven't called CreateOverlay yet */ return -EINVAL; + if (ulWidth == 0 || ulWidth == 0xffffffff || + ulHeight == 0 || ulHeight == 0xffffffff || + (x < 2 && ulWidth + 2 == 0)) + return -EINVAL; + /* Stop Ramdac Output */ DisableRamdacOutput(deviceInfo.pSTGReg);
The user can pass in any value to the driver through the 'ioctl' interface. The driver dost not check, which may cause DoS bugs. The following log reveals it: divide error: 0000 [#1] PREEMPT SMP KASAN PTI RIP: 0010:SetOverlayViewPort+0x133/0x5f0 drivers/video/fbdev/kyro/STG4000OverlayDevice.c:476 Call Trace: kyro_dev_overlay_viewport_set drivers/video/fbdev/kyro/fbdev.c:378 [inline] kyrofb_ioctl+0x2eb/0x330 drivers/video/fbdev/kyro/fbdev.c:603 do_fb_ioctl+0x1f3/0x700 drivers/video/fbdev/core/fbmem.c:1171 fb_ioctl+0xeb/0x130 drivers/video/fbdev/core/fbmem.c:1185 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x19b/0x220 fs/ioctl.c:739 do_syscall_64+0x32/0x80 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> --- Changes in v2: - Validate the inputs on a higher level --- drivers/video/fbdev/kyro/fbdev.c | 5 +++++ 1 file changed, 5 insertions(+)