* drm_modes: signed integer overflow
@ 2020-10-22 3:13 Randy Dunlap
2020-10-22 10:14 ` [Intel-gfx] " Ville Syrjälä
0 siblings, 1 reply; 5+ messages in thread
From: Randy Dunlap @ 2020-10-22 3:13 UTC (permalink / raw)
To: dri-devel, LKML, David Airlie, Daniel Vetter, intel-gfx
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 <rdunlap@infradead.org>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Intel-gfx] drm_modes: signed integer overflow
2020-10-22 3:13 drm_modes: signed integer overflow Randy Dunlap
@ 2020-10-22 10:14 ` Ville Syrjälä
2020-10-23 15:14 ` Simon Ser
0 siblings, 1 reply; 5+ messages in thread
From: Ville Syrjälä @ 2020-10-22 10:14 UTC (permalink / raw)
To: Randy Dunlap; +Cc: dri-devel, LKML, David Airlie, Daniel Vetter, intel-gfx
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
--
Ville Syrjälä
Intel
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Intel-gfx] drm_modes: signed integer overflow
2020-10-22 10:14 ` [Intel-gfx] " Ville Syrjälä
@ 2020-10-23 15:14 ` Simon Ser
2020-10-23 15:27 ` Ville Syrjälä
0 siblings, 1 reply; 5+ messages in thread
From: Simon Ser @ 2020-10-23 15:14 UTC (permalink / raw)
To: Ville Syrjälä
Cc: Randy Dunlap, David Airlie, intel-gfx, LKML, dri-devel, Pekka Paalanen
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).
[1]: https://github.com/swaywm/wlroots/pull/2450
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Intel-gfx] drm_modes: signed integer overflow
2020-10-23 15:14 ` Simon Ser
@ 2020-10-23 15:27 ` Ville Syrjälä
2020-10-23 16:02 ` Simon Ser
0 siblings, 1 reply; 5+ messages in thread
From: Ville Syrjälä @ 2020-10-23 15:27 UTC (permalink / raw)
To: Simon Ser
Cc: Randy Dunlap, David Airlie, intel-gfx, LKML, dri-devel, Pekka Paalanen
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).
>
> [1]: https://github.com/swaywm/wlroots/pull/2450
What's with those 1000000LL constants? Are you storing
clock in Hz units?
--
Ville Syrjälä
Intel
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Intel-gfx] drm_modes: signed integer overflow
2020-10-23 15:27 ` Ville Syrjälä
@ 2020-10-23 16:02 ` Simon Ser
0 siblings, 0 replies; 5+ messages in thread
From: Simon Ser @ 2020-10-23 16:02 UTC (permalink / raw)
To: Ville Syrjälä
Cc: Randy Dunlap, David Airlie, intel-gfx, LKML, dri-devel, Pekka Paalanen
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).
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-10-23 16:02 UTC | newest]
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2020-10-22 3:13 drm_modes: signed integer overflow Randy Dunlap
2020-10-22 10:14 ` [Intel-gfx] " Ville Syrjälä
2020-10-23 15:14 ` Simon Ser
2020-10-23 15:27 ` Ville Syrjälä
2020-10-23 16:02 ` Simon Ser
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