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] ================================================================================
--
~Randy
Reported-by: Randy Dunlap <[email protected]>
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 <[email protected]>
> _______________________________________________
> Intel-gfx mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Ville Syrj?l?
Intel
On Thursday, October 22, 2020 12:14 PM, Ville Syrjälä <[email protected]> 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).
[1]: https://github.com/swaywm/wlroots/pull/2450