Am 14.07.20 um 09:41 schrieb Thomas Zimmermann: > Hi > > Am 10.07.20 um 10:24 schrieb butt3rflyh4ck: >> 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 >> 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. > > Thanks for reporting. I think we recently had a patch for this problem, > [1] but I asked for some changes. Are you in a position to test a fix? > > Best regards > Thomas > > > [1] > https://lore.kernel.org/dri-devel/20200620062134.82961-1-jiayang5@huawei.com/ I sent out a patchset with this patch and a few additional changes. https://lore.kernel.org/dri-devel/20200714083238.28479-1-tzimmermann@suse.de/T/#t Best regards Thomas > >> >> crash log: >> ================================================================== >> BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120 >> drivers/gpu/drm/drm_gem.c:953 >> Read of size 8 at addr ffff888064dfd928 by task syz-executor.2/1320 >> >> CPU: 1 PID: 1320 Comm: syz-executor.2 Not tainted 5.8.0-rc4+ #1 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS >> 1.10.2-1ubuntu1 04/01/2014 >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x18f/0x20d lib/dump_stack.c:118 >> print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383 >> __kasan_report mm/kasan/report.c:513 [inline] >> kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 >> drm_gem_object_release+0xf7/0x120 drivers/gpu/drm/drm_gem.c:953 >> drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:211 [inline] >> drm_gem_vram_create+0x3e6/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244 >> drm_gem_vram_fill_create_dumb+0x17a/0x310 >> drivers/gpu/drm/drm_gem_vram_helper.c:615 >> drm_gem_vram_driver_dumb_create+0x51/0xb0 >> drivers/gpu/drm/drm_gem_vram_helper.c:710 >> drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94 >> drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787 >> drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887 >> vfs_ioctl fs/ioctl.c:48 [inline] >> ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 >> __do_sys_ioctl fs/ioctl.c:762 [inline] >> __se_sys_ioctl fs/ioctl.c:760 [inline] >> __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 >> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> RIP: 0033:0x467a29 >> Code: Bad RIP value. >> RSP: 002b:00007f98f2d40c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 >> RAX: ffffffffffffffda RBX: 000000000076bf00 RCX: 0000000000467a29 >> RDX: 0000000020000040 RSI: 00000000c02064b2 RDI: 0000000000000003 >> RBP: 000000000070c600 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f98f2d416bc >> R13: 0000000000000297 R14: 0000000000702040 R15: 00000000004d2418 >> >> Allocated by task 1320: >> save_stack+0x1b/0x40 mm/kasan/common.c:48 >> set_track mm/kasan/common.c:56 [inline] >> __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494 >> kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551 >> kmalloc include/linux/slab.h:555 [inline] >> kzalloc include/linux/slab.h:669 [inline] >> drm_gem_vram_create+0x425/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:239 >> drm_gem_vram_fill_create_dumb+0x17a/0x310 >> drivers/gpu/drm/drm_gem_vram_helper.c:615 >> drm_gem_vram_driver_dumb_create+0x51/0xb0 >> drivers/gpu/drm/drm_gem_vram_helper.c:710 >> drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94 >> drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787 >> drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887 >> vfs_ioctl fs/ioctl.c:48 [inline] >> ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 >> __do_sys_ioctl fs/ioctl.c:762 [inline] >> __se_sys_ioctl fs/ioctl.c:760 [inline] >> __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 >> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> Freed by task 1320: >> save_stack+0x1b/0x40 mm/kasan/common.c:48 >> set_track mm/kasan/common.c:56 [inline] >> kasan_set_free_info mm/kasan/common.c:316 [inline] >> __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455 >> __cache_free mm/slab.c:3426 [inline] >> kfree+0x103/0x2c0 mm/slab.c:3757 >> ttm_bo_release+0xae1/0x1350 drivers/gpu/drm/ttm/ttm_bo.c:632 >> kref_put include/linux/kref.h:65 [inline] >> ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:638 [inline] >> ttm_bo_init_reserved+0xb04/0xd00 drivers/gpu/drm/ttm/ttm_bo.c:1339 >> ttm_bo_init+0x10e/0x330 drivers/gpu/drm/ttm/ttm_bo.c:1366 >> drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:202 [inline] >> drm_gem_vram_create+0x3c1/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244 >> drm_gem_vram_fill_create_dumb+0x17a/0x310 >> drivers/gpu/drm/drm_gem_vram_helper.c:615 >> drm_gem_vram_driver_dumb_create+0x51/0xb0 >> drivers/gpu/drm/drm_gem_vram_helper.c:710 >> drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94 >> drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787 >> drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887 >> vfs_ioctl fs/ioctl.c:48 [inline] >> ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 >> __do_sys_ioctl fs/ioctl.c:762 [inline] >> __se_sys_ioctl fs/ioctl.c:760 [inline] >> __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 >> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> The buggy address belongs to the object at ffff888064dfd800 >> which belongs to the cache kmalloc-1k of size 1024 >> The buggy address is located 296 bytes inside of >> 1024-byte region [ffff888064dfd800, ffff888064dfdc00) >> The buggy address belongs to the page: >> page:ffffea0001937f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 >> flags: 0xfffe0000000200(slab) >> raw: 00fffe0000000200 ffffea0000f3c248 ffffea0001ad7388 ffff88806bc00c40 >> raw: 0000000000000000 ffff888064dfd000 0000000100000002 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff888064dfd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff888064dfd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff888064dfd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ^ >> ffff888064dfd980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff888064dfda00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ================================================================== >> >> Regards, >> butt3rflyh4ck. >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >> > -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer