From: Zwane Mwaikambo <zwanem@gmail.com> To: tcamuso@redhat.com Cc: Linux Kernel <linux-kernel@vger.kernel.org>, dri-devel@lists.freedesktop.org, dkwon@redhat.com Subject: Re: [PATCH] drm: assure aux_dev is nonzero before using it Date: Mon, 10 Aug 2020 10:11:50 -0700 (PDT) [thread overview] Message-ID: <alpine.DEB.2.21.2008101004110.27032@montezuma.home> (raw) Hi Folks, I know this thread eventually dropped off due to not identifying the underlying issue. It's still occuring on 5.8 and in my case it happened because the udev device nodes for the DP aux devices were not cleaned up whereas the kernel had no association with them. I can reproduce the bug just by creating a device node for a non-existent minor device and calling open(). To me it still makes sense to just check aux_dev because the chardev has no way to check before calling. (gdb) list *drm_dp_aux_dev_get_by_minor+0x29 0x17b39 is in drm_dp_aux_dev_get_by_minor (drivers/gpu/drm/drm_dp_aux_dev.c:65). 60 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index) 61 { 62 struct drm_dp_aux_dev *aux_dev = NULL; 63 64 mutex_lock(&aux_idr_mutex); 65 aux_dev = idr_find(&aux_idr, index); 66 if (!kref_get_unless_zero(&aux_dev->refcount)) 67 aux_dev = NULL; 68 mutex_unlock(&aux_idr_mutex); 69 (gdb) p/x &((struct drm_dp_aux_dev *)(0x0))->refcount $8 = 0x18 static int auxdev_open(struct inode *inode, struct file *file) { unsigned int minor = iminor(inode); struct drm_dp_aux_dev *aux_dev; aux_dev = drm_dp_aux_dev_get_by_minor(minor); if (!aux_dev) return -ENODEV; file->private_data = aux_dev; return 0; }
WARNING: multiple messages have this Message-ID (diff)
From: Zwane Mwaikambo <zwanem@gmail.com> To: tcamuso@redhat.com Cc: dkwon@redhat.com, Linux Kernel <linux-kernel@vger.kernel.org>, dri-devel@lists.freedesktop.org Subject: Re: [PATCH] drm: assure aux_dev is nonzero before using it Date: Mon, 10 Aug 2020 10:11:50 -0700 (PDT) [thread overview] Message-ID: <alpine.DEB.2.21.2008101004110.27032@montezuma.home> (raw) Hi Folks, I know this thread eventually dropped off due to not identifying the underlying issue. It's still occuring on 5.8 and in my case it happened because the udev device nodes for the DP aux devices were not cleaned up whereas the kernel had no association with them. I can reproduce the bug just by creating a device node for a non-existent minor device and calling open(). To me it still makes sense to just check aux_dev because the chardev has no way to check before calling. (gdb) list *drm_dp_aux_dev_get_by_minor+0x29 0x17b39 is in drm_dp_aux_dev_get_by_minor (drivers/gpu/drm/drm_dp_aux_dev.c:65). 60 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index) 61 { 62 struct drm_dp_aux_dev *aux_dev = NULL; 63 64 mutex_lock(&aux_idr_mutex); 65 aux_dev = idr_find(&aux_idr, index); 66 if (!kref_get_unless_zero(&aux_dev->refcount)) 67 aux_dev = NULL; 68 mutex_unlock(&aux_idr_mutex); 69 (gdb) p/x &((struct drm_dp_aux_dev *)(0x0))->refcount $8 = 0x18 static int auxdev_open(struct inode *inode, struct file *file) { unsigned int minor = iminor(inode); struct drm_dp_aux_dev *aux_dev; aux_dev = drm_dp_aux_dev_get_by_minor(minor); if (!aux_dev) return -ENODEV; file->private_data = aux_dev; return 0; } _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next reply other threads:[~2020-08-10 17:20 UTC|newest] Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-10 17:11 Zwane Mwaikambo [this message] 2020-08-10 17:11 ` [PATCH] drm: assure aux_dev is nonzero before using it Zwane Mwaikambo 2020-08-11 8:58 ` Daniel Vetter 2020-08-11 8:58 ` Daniel Vetter 2020-08-11 22:16 ` Zwane Mwaikambo 2020-08-11 22:16 ` Zwane Mwaikambo 2020-08-12 14:10 ` Daniel Vetter 2020-08-12 14:10 ` Daniel Vetter 2020-08-12 15:44 ` Lyude Paul 2020-08-12 15:44 ` Lyude Paul 2020-08-12 20:21 ` Zwane Mwaikambo 2020-08-12 20:21 ` Zwane Mwaikambo 2020-09-04 7:21 ` [PATCH]] drm/dp check aux_dev before use in drm_dp_aux_dev_get_by_minor() Zwane Mwaikambo 2020-09-04 7:21 ` Zwane Mwaikambo 2020-09-07 11:05 ` Ville Syrjälä 2020-09-07 11:05 ` Ville Syrjälä 2020-09-08 16:18 ` Zwane Mwaikambo 2020-09-08 16:18 ` Zwane Mwaikambo 2020-08-18 17:58 ` [PATCH] drm: assure aux_dev is nonzero before using it Zwane Mwaikambo 2020-08-18 17:58 ` Zwane Mwaikambo 2020-09-08 18:41 ` Lyude Paul 2020-09-08 18:41 ` Lyude Paul -- strict thread matches above, loose matches on Subject: below -- 2019-05-23 11:09 tcamuso 2019-05-23 11:09 ` tcamuso 2019-05-24 8:36 ` Jani Nikula 2019-05-24 8:36 ` Jani Nikula 2019-05-24 10:48 ` tony camuso 2019-05-24 11:58 ` Ville Syrjälä 2019-07-10 13:47 ` Tony Camuso 2019-07-10 13:56 ` Ville Syrjälä 2019-07-12 16:07 ` Tony Camuso 2019-07-12 17:06 ` Ville Syrjälä 2019-07-12 17:35 ` Tony Camuso 2019-09-23 15:03 ` Tony Camuso 2019-09-23 15:22 ` Ville Syrjälä
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