Hi,
With linux-next 20201021, when booting up, I am seeing this:
[ 0.560896] UBSAN: signed-integer-overflow in ../drivers/gpu/drm/drm_modes.c:765:20 [ 0.560903] 2376000 * 1000 cannot be represented in type 'int' [ 0.560909] CPU: 3 PID: 7 Comm: kworker/u16:0 Not tainted 5.9.0-next-20201021 #2 [ 0.560914] Hardware name: TOSHIBA PORTEGE R835/Portable PC, BIOS Version 4.10 01/08/2013 [ 0.560924] Workqueue: events_unbound async_run_entry_fn
[ 0.560930] Call Trace: [ 0.560938] dump_stack+0x5e/0x74 [ 0.560943] ubsan_epilogue+0x9/0x45 [ 0.560948] handle_overflow+0x8b/0x98 [ 0.560953] ? set_track+0x3f/0xad [ 0.560958] __ubsan_handle_mul_overflow+0xe/0x10 [ 0.560964] drm_mode_vrefresh+0x4a/0xbc [ 0.560970] initcall i915_init+0x0/0x6a returned 0 after 116076 usecs [ 0.560974] calling cn_proc_init+0x0/0x36 @ 1 [ 0.560978] cea_mode_alternate_clock+0x11/0x62 [ 0.560985] drm_match_cea_mode+0xc7/0x1e7 [ 0.560987] initcall cn_proc_init+0x0/0x36 returned 0 after 3 usecs [ 0.560990] calling topology_sysfs_init+0x0/0x2d @ 1 [ 0.561000] drm_mode_validate_ycbcr420+0xd/0x48 [ 0.561005] drm_helper_probe_single_connector_modes+0x6db/0x7da [ 0.561012] drm_client_modeset_probe+0x225/0x143f [ 0.561018] ? bitmap_fold+0x8a/0x8a [ 0.561023] ? update_cfs_rq_load_avg+0x192/0x1a2 [ 0.561029] __drm_fb_helper_initial_config_and_unlock+0x3f/0x5b7 [ 0.561035] ? get_sd_balance_interval+0x1c/0x40 [ 0.561040] drm_fb_helper_initial_config+0x48/0x4f [ 0.561047] intel_fbdev_initial_config+0x13/0x23 [ 0.561052] async_run_entry_fn+0x89/0x15c [ 0.561058] process_one_work+0x15c/0x1f3 [ 0.561064] worker_thread+0x1ac/0x25d [ 0.561069] ? process_scheduled_works+0x2e/0x2e [ 0.561074] kthread+0x10e/0x116 [ 0.561078] ? kthread_parkme+0x1c/0x1c [ 0.561083] ret_from_fork+0x22/0x30 [ 0.561087] ================================================================================
On Wed, Oct 21, 2020 at 08:13:43PM -0700, Randy Dunlap wrote:
Hi,
With linux-next 20201021, when booting up, I am seeing this:
[ 0.560896] UBSAN: signed-integer-overflow in ../drivers/gpu/drm/drm_modes.c:765:20 [ 0.560903] 2376000 * 1000 cannot be represented in type 'int'
Dang. Didn't realize these new crazy >8k modes have dotclocks reaching almost 6 GHz, which would overflow even u32. I guess we'll switch to 64bit maths. Now I wonder how many other places can hit this overflow in practice...
[ 0.560909] CPU: 3 PID: 7 Comm: kworker/u16:0 Not tainted 5.9.0-next-20201021 #2 [ 0.560914] Hardware name: TOSHIBA PORTEGE R835/Portable PC, BIOS Version 4.10 01/08/2013 [ 0.560924] Workqueue: events_unbound async_run_entry_fn
[ 0.560930] Call Trace: [ 0.560938] dump_stack+0x5e/0x74 [ 0.560943] ubsan_epilogue+0x9/0x45 [ 0.560948] handle_overflow+0x8b/0x98 [ 0.560953] ? set_track+0x3f/0xad [ 0.560958] __ubsan_handle_mul_overflow+0xe/0x10 [ 0.560964] drm_mode_vrefresh+0x4a/0xbc [ 0.560970] initcall i915_init+0x0/0x6a returned 0 after 116076 usecs [ 0.560974] calling cn_proc_init+0x0/0x36 @ 1 [ 0.560978] cea_mode_alternate_clock+0x11/0x62 [ 0.560985] drm_match_cea_mode+0xc7/0x1e7 [ 0.560987] initcall cn_proc_init+0x0/0x36 returned 0 after 3 usecs [ 0.560990] calling topology_sysfs_init+0x0/0x2d @ 1 [ 0.561000] drm_mode_validate_ycbcr420+0xd/0x48 [ 0.561005] drm_helper_probe_single_connector_modes+0x6db/0x7da [ 0.561012] drm_client_modeset_probe+0x225/0x143f [ 0.561018] ? bitmap_fold+0x8a/0x8a [ 0.561023] ? update_cfs_rq_load_avg+0x192/0x1a2 [ 0.561029] __drm_fb_helper_initial_config_and_unlock+0x3f/0x5b7 [ 0.561035] ? get_sd_balance_interval+0x1c/0x40 [ 0.561040] drm_fb_helper_initial_config+0x48/0x4f [ 0.561047] intel_fbdev_initial_config+0x13/0x23 [ 0.561052] async_run_entry_fn+0x89/0x15c [ 0.561058] process_one_work+0x15c/0x1f3 [ 0.561064] worker_thread+0x1ac/0x25d [ 0.561069] ? process_scheduled_works+0x2e/0x2e [ 0.561074] kthread+0x10e/0x116 [ 0.561078] ? kthread_parkme+0x1c/0x1c [ 0.561083] ret_from_fork+0x22/0x30 [ 0.561087] ================================================================================
-- ~Randy Reported-by: Randy Dunlap rdunlap@infradead.org _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Thursday, October 22, 2020 12:14 PM, Ville Syrjälä ville.syrjala@linux.intel.com wrote:
On Wed, Oct 21, 2020 at 08:13:43PM -0700, Randy Dunlap wrote:
Hi, With linux-next 20201021, when booting up, I am seeing this: [ 0.560896] UBSAN: signed-integer-overflow in ../drivers/gpu/drm/drm_modes.c:765:20 [ 0.560903] 2376000 * 1000 cannot be represented in type 'int'
Dang. Didn't realize these new crazy >8k modes have dotclocks reaching almost 6 GHz, which would overflow even u32. I guess we'll switch to 64bit maths. Now I wonder how many other places can hit this overflow in practice...
Can you provide an example of a full crazy >8k mode? I'm trying to get a fix for my user-space [1], and I'm wondering if int32_t is enough after dividing by mode->htotal.
CC Pekka, just FYI (I think Weston has similar code).
On Fri, Oct 23, 2020 at 03:14:20PM +0000, Simon Ser wrote:
On Thursday, October 22, 2020 12:14 PM, Ville Syrjälä ville.syrjala@linux.intel.com wrote:
On Wed, Oct 21, 2020 at 08:13:43PM -0700, Randy Dunlap wrote:
Hi, With linux-next 20201021, when booting up, I am seeing this: [ 0.560896] UBSAN: signed-integer-overflow in ../drivers/gpu/drm/drm_modes.c:765:20 [ 0.560903] 2376000 * 1000 cannot be represented in type 'int'
Dang. Didn't realize these new crazy >8k modes have dotclocks reaching almost 6 GHz, which would overflow even u32. I guess we'll switch to 64bit maths. Now I wonder how many other places can hit this overflow in practice...
Can you provide an example of a full crazy >8k mode?
These are two extreme cases: /* 216 - 10240x4320@100Hz 64:27 */ { DRM_MODE("10240x4320", DRM_MODE_TYPE_DRIVER, 5940000, 10240, 12432, 12608, 13200, 0, 4320, 4336, 4356, 4500, 0, DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC), .picture_aspect_ratio = HDMI_PICTURE_ASPECT_64_27, }, /* 217 - 10240x4320@120Hz 64:27 */ { DRM_MODE("10240x4320", DRM_MODE_TYPE_DRIVER, 5940000, 10240, 10528, 10704, 11000, 0, 4320, 4336, 4356, 4500, 0, DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC), .picture_aspect_ratio = HDMI_PICTURE_ASPECT_64_27, }
I'm trying to get a fix for my user-space [1], and I'm wondering if int32_t is enough after dividing by mode->htotal.
CC Pekka, just FYI (I think Weston has similar code).
What's with those 1000000LL constants? Are you storing clock in Hz units?
On Friday, October 23, 2020 5:27 PM, Ville Syrjälä ville.syrjala@linux.intel.com wrote:
These are two extreme cases:
Thanks!
I'm trying to get a fix for my user-space 1, and I'm wondering if int32_t is enough after dividing by mode->htotal. CC Pekka, just FYI (I think Weston has similar code).
What's with those 1000000LL constants? Are you storing clock in Hz units?
We're storing the vertical refresh rate in mHz (milli-Hertz).
dri-devel@lists.freedesktop.org
-
Randy Dunlap -
Simon Ser -
Ville Syrjälä