@@ -100,7 +100,8 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data)
WARN_ON(dev != minor->dev);
- put_device(minor->kdev);
+ if (minor->kdev)
+ put_device(minor->kdev);
spin_lock_irqsave(&drm_minor_lock, flags);
idr_remove(&drm_minors_idr, minor->index);
@@ -140,8 +141,11 @@ static int drm_minor_alloc(struct drm_device *dev, unsigned int type)
return r;
minor->kdev = drm_sysfs_minor_alloc(minor);
- if (IS_ERR(minor->kdev))
- return PTR_ERR(minor->kdev);
+ if (IS_ERR(minor->kdev)) {
+ r = PTR_ERR(minor->kdev);
+ minor->kdev = NULL;
+ return r;
+ }
*drm_minor_get_slot(dev, type) = minor;
return 0;
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 0 PID: 18491 Comm: syz-executor.0 Tainted: G C 5.10.0-rc4+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 RIP: 0010:kobject_put+0x2f/0x140 Call Trace: put_device+0x20/0x40 drm_minor_alloc_release+0x60/0xe0 [drm] drm_managed_release+0x1b6/0x440 [drm] drm_dev_init+0x50b/0x8e0 [drm] __devm_drm_dev_alloc+0x50/0x160 [drm] vgem_init+0x15c/0x1000 [vgem] do_one_initcall+0x149/0x7e0 do_init_module+0x1ef/0x700 load_module+0x3467/0x4140 __do_sys_finit_module+0x10d/0x1a0 do_syscall_64+0x34/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa9 kfree(minor->kdev) in put_device would raise a null-ptr-deref bug when minor->kdev is null or error pointer. So do check before put_device in drm_minor_alloc_release and prohibit minor->kdev becoming an error pointer. Fixes: f96306f9892b ("drm: manage drm_minor cleanup with drmm_") Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com> --- drivers/gpu/drm/drm_drv.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)