On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote: > I report a bug (in linux-5.8.0-rc4) found by syzkaller. > > kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config > > I test the reproducer and crash too. > > In the drm_em_vram_t() function, ttm_bo_init() function call ^^^^^^^^^^^^^ This a typo. The function name is drm_gem_vram_init(). > ttm_bo_init_reserved(), > the ttm_bo_init_reserved() function call ttm_bo_put(), it will free > gbo->bo that is struct ttm_buffer_object. > > then, goto the err_drm_gem_object_release lable, > drm_gem_object_release() function will free gbo->bo.base, so cause use > after free. > There is a third free in drm_gem_vram_create(). This is a triple free bug. The correct place to free this is in drm_gem_vram_create() because that's where it was allocated. This code is quite subtle so I'm not going to attempt to fix it because I can't test it. regards, dan carpenter _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
