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@oracle.com --- 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);