The drm_pending_event can be freed by drm_send_event_locked, as a result we should call trace_drm_vblank_event_delivered before this to avoid hitting a user-after-free error when accessing the pid member:
[ 378.438497] BUG: KASAN: use-after-free in send_vblank_event+0xf0/0x310 [drm] at addr ffff8801ac7e50a0 [ 378.438500] Read of size 4 by task Xorg/1562 [ 378.438501] ============================================================================= [ 378.438504] BUG kmalloc-128 (Tainted: G B ): kasan: bad access detected [ 378.438506] -----------------------------------------------------------------------------
[ 378.438509] INFO: Freed in 0x10001309c age=18446737369265680575 cpu=0 pid=0 [ 378.438541] drm_send_event_locked+0x207/0x2f0 [drm] [ 378.438544] __slab_free+0x24c/0x650 [ 378.438546] kfree+0x3a2/0x760 [ 378.438578] drm_send_event_locked+0x207/0x2f0 [drm] [ 378.438610] send_vblank_event+0xb7/0x310 [drm] [ 378.438643] drm_crtc_send_vblank_event+0x130/0x1f0 [drm] [ 378.438722] intel_atomic_commit_tail+0x23b5/0x53f0 [i915] [ 378.438802] intel_atomic_commit+0xbae/0x12f0 [i915] [ 378.438839] drm_atomic_commit+0xb0/0x120 [drm] [ 378.438855] drm_atomic_helper_connector_dpms+0x339/0x5d0 [drm_kms_helper] [ 378.438891] drm_mode_obj_set_property_ioctl+0x8f1/0xcc0 [drm] [ 378.438927] drm_mode_connector_property_set_ioctl+0xf3/0x170 [drm] [ 378.438959] drm_ioctl+0x2d7/0xae0 [drm] [ 378.438962] do_vfs_ioctl+0x1c9/0x1280 [ 378.438964] SyS_ioctl+0x79/0x90 [ 378.438967] entry_SYSCALL_64_fastpath+0x1a/0xa4
Cc: dri-devel@lists.freedesktop.org Cc: Daniel Vetter daniel.vetter@intel.com Signed-off-by: Matthew Auld matthew.auld@intel.com --- drivers/gpu/drm/drm_irq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 76e39c5..8ca3d2b 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -994,10 +994,10 @@ static void send_vblank_event(struct drm_device *dev, e->event.tv_sec = now->tv_sec; e->event.tv_usec = now->tv_usec;
- drm_send_event_locked(dev, &e->base); - trace_drm_vblank_event_delivered(e->base.pid, e->pipe, e->event.sequence); + + drm_send_event_locked(dev, &e->base); }
/**
On Mon, Jun 20, 2016 at 05:42:46PM +0100, Matthew Auld wrote:
The drm_pending_event can be freed by drm_send_event_locked, as a result we should call trace_drm_vblank_event_delivered before this to avoid hitting a user-after-free error when accessing the pid member:
[ 378.438497] BUG: KASAN: use-after-free in send_vblank_event+0xf0/0x310 [drm] at addr ffff8801ac7e50a0 [ 378.438500] Read of size 4 by task Xorg/1562 [ 378.438501] ============================================================================= [ 378.438504] BUG kmalloc-128 (Tainted: G B ): kasan: bad access detected [ 378.438506] -----------------------------------------------------------------------------
[ 378.438509] INFO: Freed in 0x10001309c age=18446737369265680575 cpu=0 pid=0 [ 378.438541] drm_send_event_locked+0x207/0x2f0 [drm] [ 378.438544] __slab_free+0x24c/0x650 [ 378.438546] kfree+0x3a2/0x760 [ 378.438578] drm_send_event_locked+0x207/0x2f0 [drm] [ 378.438610] send_vblank_event+0xb7/0x310 [drm] [ 378.438643] drm_crtc_send_vblank_event+0x130/0x1f0 [drm] [ 378.438722] intel_atomic_commit_tail+0x23b5/0x53f0 [i915] [ 378.438802] intel_atomic_commit+0xbae/0x12f0 [i915] [ 378.438839] drm_atomic_commit+0xb0/0x120 [drm] [ 378.438855] drm_atomic_helper_connector_dpms+0x339/0x5d0 [drm_kms_helper] [ 378.438891] drm_mode_obj_set_property_ioctl+0x8f1/0xcc0 [drm] [ 378.438927] drm_mode_connector_property_set_ioctl+0xf3/0x170 [drm] [ 378.438959] drm_ioctl+0x2d7/0xae0 [drm] [ 378.438962] do_vfs_ioctl+0x1c9/0x1280 [ 378.438964] SyS_ioctl+0x79/0x90 [ 378.438967] entry_SYSCALL_64_fastpath+0x1a/0xa4
Cc: dri-devel@lists.freedesktop.org Cc: Daniel Vetter daniel.vetter@intel.com Signed-off-by: Matthew Auld matthew.auld@intel.com
Nice catch, applied to drm-misc.
Thanks, Daniel
drivers/gpu/drm/drm_irq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 76e39c5..8ca3d2b 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -994,10 +994,10 @@ static void send_vblank_event(struct drm_device *dev, e->event.tv_sec = now->tv_sec; e->event.tv_usec = now->tv_usec;
- drm_send_event_locked(dev, &e->base);
- trace_drm_vblank_event_delivered(e->base.pid, e->pipe, e->event.sequence);
- drm_send_event_locked(dev, &e->base);
}
/**
2.5.5
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dri-devel@lists.freedesktop.org
-
Daniel Vetter -
Matthew Auld