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/ > > 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, 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