Do a sanity check on struct drm_format_info hsub and vsub values to
avoid divide by zero.
Syzkaller reported a divide error in framebuffer_check() when the
DRM_FORMAT_Q410 or DRM_FORMAT_Q401 pixel_format is passed in via
the DRM_IOCTL_MODE_ADDFB2 ioctl. The drm_format_info struct for
the DRM_FORMAT_Q410 pixel_pattern has ".hsub = 0" and ".vsub = 0".
fb_plane_width() uses hsub as a divisor and fb_plane_height() uses
vsub as a divisor. These divisors need to be sanity checked for
zero before use.
divide error: 0000 [#1] SMP KASAN NOPTI
CPU: 0 PID: 14995 Comm: syz-executor709 Not tainted 5.15.0-rc6-syzk #1
Hardware name: Red Hat KVM, BIOS 1.13.0-2
RIP: 0010:framebuffer_check drivers/gpu/drm/drm_framebuffer.c:199 [inline]
RIP: 0010:drm_internal_framebuffer_create+0x604/0xf90
drivers/gpu/drm/drm_framebuffer.c:317
Call Trace:
drm_mode_addfb2+0xdc/0x320 drivers/gpu/drm/drm_framebuffer.c:355
drm_mode_addfb2_ioctl+0x2a/0x40 drivers/gpu/drm/drm_framebuffer.c:391
drm_ioctl_kernel+0x23a/0x2e0 drivers/gpu/drm/drm_ioctl.c:795
drm_ioctl+0x589/0xac0 drivers/gpu/drm/drm_ioctl.c:898
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Signed-off-by: George Kennedy <george.kennedy@xxxxxxxxxx>
---
drivers/gpu/drm/drm_framebuffer.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
index 07f5abc..a146e4b 100644
--- a/drivers/gpu/drm/drm_framebuffer.c
+++ b/drivers/gpu/drm/drm_framebuffer.c
@@ -195,6 +195,16 @@ static int framebuffer_check(struct drm_device *dev,
/* now let the driver pick its own format info */
info = drm_get_format_info(dev, r);
+ if (info->hsub == 0) {
+ DRM_DEBUG_KMS("bad horizontal chroma subsampling factor %u\n", info->hsub);
+ return -EINVAL;
+ }
+
+ if (info->vsub == 0) {
+ DRM_DEBUG_KMS("bad vertical chroma subsampling factor %u\n", info->vsub);
+ return -EINVAL;
+ }
+
for (i = 0; i < info->num_planes; i++) {
unsigned int width = fb_plane_width(r->width, info, i);
unsigned int height = fb_plane_height(r->height, info, i);
--
1.8.3.1
