Messages in this thread | | | Date | Mon, 21 Jul 2014 14:56:44 +0400 | From | Andrey Tsyvarev <> | Subject | f2fs: Possible use-after-free when umount filesystem |
| |
Hello,
Using memory error detector reveals the following use-after-free error in 3.15.0:
AddressSanitizer: heap-use-after-free in f2fs_evict_inode Read of size 8 by thread T22279: [<ffffffffa02d8702>] f2fs_evict_inode+0x102/0x2e0 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/f2fs.h:584 [<ffffffff812359af>] evict+0x15f/0x290 /home/tester/linux-sources/linux-kasan/fs/inode.c:550 [< inlined >] iput+0x196/0x280 iput_final /home/tester/linux-sources/linux-kasan/fs/inode.c:1418 [<ffffffff812369a6>] iput+0x196/0x280 /home/tester/linux-sources/linux-kasan/fs/inode.c:1436 [<ffffffffa02dc416>] f2fs_put_super+0xd6/0x170 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/super.c:434 [<ffffffff81210095>] generic_shutdown_super+0xc5/0x1b0 /home/tester/linux-sources/linux-kasan/fs/super.c:406 [<ffffffff812105fd>] kill_block_super+0x4d/0xb0 /home/tester/linux-sources/linux-kasan/fs/super.c:1019 [<ffffffff81210a86>] deactivate_locked_super+0x66/0x80 /home/tester/linux-sources/linux-kasan/fs/super.c:284 [<ffffffff81211c98>] deactivate_super+0x68/0x80 /home/tester/linux-sources/linux-kasan/fs/super.c:307 [<ffffffff8123cc88>] mntput_no_expire+0x198/0x250 /home/tester/linux-sources/linux-kasan/fs/namespace.c:986 (discriminator 3) [< inlined >] SyS_umount+0xe9/0x1a0 SYSC_umount /home/tester/linux-sources/linux-kasan/fs/namespace.c:1424 [<ffffffff8123f1c9>] SyS_umount+0xe9/0x1a0 /home/tester/linux-sources/linux-kasan/fs/namespace.c:1392 [<ffffffff81cc8df9>] system_call_fastpath+0x16/0x1b /home/tester/linux-sources/linux-kasan/arch/x86/kernel/entry_64.S:426
Freed by thread T3: [<ffffffffa02dc337>] f2fs_i_callback+0x27/0x30 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/super.c:408 [< inlined >] rcu_process_callbacks+0x2d6/0x930 __rcu_reclaim /home/tester/linux-sources/linux-kasan/kernel/rcu/rcu.h:114 [< inlined >] rcu_process_callbacks+0x2d6/0x930 rcu_do_batch /home/tester/linux-sources/linux-kasan/kernel/rcu/tree.c:2242 [< inlined >] rcu_process_callbacks+0x2d6/0x930 invoke_rcu_callbacks /home/tester/linux-sources/linux-kasan/kernel/rcu/tree.c:2499 [< inlined >] rcu_process_callbacks+0x2d6/0x930 __rcu_process_callbacks /home/tester/linux-sources/linux-kasan/kernel/rcu/tree.c:2466 [<ffffffff810fd266>] rcu_process_callbacks+0x2d6/0x930 /home/tester/linux-sources/linux-kasan/kernel/rcu/tree.c:2483 [<ffffffff8107cce2>] __do_softirq+0x142/0x380 /home/tester/linux-sources/linux-kasan/kernel/softirq.c:269 [<ffffffff8107cf50>] run_ksoftirqd+0x30/0x50 /home/tester/linux-sources/linux-kasan/kernel/softirq.c:658 [<ffffffff810b2a87>] smpboot_thread_fn+0x197/0x280 /home/tester/linux-sources/linux-kasan/kernel/smpboot.c:160 [<ffffffff810a8238>] kthread+0x148/0x160 /home/tester/linux-sources/linux-kasan/kernel/kthread.c:207 [<ffffffff81cc8d4c>] ret_from_fork+0x7c/0xb0 /home/tester/linux-sources/linux-kasan/arch/x86/kernel/entry_64.S:351
Allocated by thread T22276: [<ffffffffa02dc7dd>] f2fs_alloc_inode+0x2d/0x170 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/super.c:356 [<ffffffff8123471d>] alloc_inode+0x2d/0xe0 /home/tester/linux-sources/linux-kasan/fs/inode.c:208 [<ffffffff81235e2a>] iget_locked+0x10a/0x230 /home/tester/linux-sources/linux-kasan/fs/inode.c:1085 [<ffffffffa02d7495>] f2fs_iget+0x35/0xa80 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/inode.c:129 [<ffffffffa02e2393>] f2fs_fill_super+0xb53/0xff0 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/super.c:1021 [<ffffffff81211bce>] mount_bdev+0x1de/0x240 /home/tester/linux-sources/linux-kasan/fs/super.c:992 [<ffffffffa02dbce0>] f2fs_mount+0x10/0x20 [f2fs] /home/tester/linux-sources/linux-kasan/fs/f2fs/super.c:1127 [<ffffffff81212a85>] mount_fs+0x55/0x220 /home/tester/linux-sources/linux-kasan/fs/super.c:1095 [<ffffffff8123c026>] vfs_kern_mount+0x66/0x200 /home/tester/linux-sources/linux-kasan/fs/namespace.c:851 [< inlined >] do_mount+0x2b4/0x1120 do_new_mount /home/tester/linux-sources/linux-kasan/fs/namespace.c:2129 [<ffffffff812400d4>] do_mount+0x2b4/0x1120 /home/tester/linux-sources/linux-kasan/fs/namespace.c:2453 [< inlined >] SyS_mount+0xb2/0x110 SYSC_mount /home/tester/linux-sources/linux-kasan/fs/namespace.c:2647 [<ffffffff812414a2>] SyS_mount+0xb2/0x110 /home/tester/linux-sources/linux-kasan/fs/namespace.c:2620 [<ffffffff81cc8df9>] system_call_fastpath+0x16/0x1b /home/tester/linux-sources/linux-kasan/arch/x86/kernel/entry_64.S:426
The buggy address ffff8800587866c8 is located 48 bytes inside of 680-byte region [ffff880058786698, ffff880058786940)
Memory state around the buggy address: ffff880058786100: ffffffff ffffffff ffffffff ffffffff ffff880058786200: ffffffff ffffffff ffffffrr rrrrrrrr ffff880058786300: rrrrrrrr rrffffff ffffffff ffffffff ffff880058786400: ffffffff ffffffff ffffffff ffffffff ffff880058786500: ffffffff ffffffff ffffffff fffffffr >ffff880058786600: rrrrrrrr rrrrrrrr rrrfffff ffffffff ^ ffff880058786700: ffffffff ffffffff ffffffff ffffffff ffff880058786800: ffffffff ffffffff ffffffff ffffffff ffff880058786900: ffffffff rrrrrrrr rrrrrrrr rrrr.... ffff880058786a00: ........ ........ ........ ........ ffff880058786b00: ........ ........ ........ ........ Legend: f - 8 freed bytes r - 8 redzone bytes . - 8 allocated bytes x=1..7 - x allocated bytes + (8-x) redzone bytes
Investigation shows, that f2fs_evict_inode, when called for 'meta_inode', uses invalidate_mapping_pages() for 'node_inode'. But 'node_inode' is deleted before 'meta_inode' in f2fs_put_super via iput().
It seems that in common usage scenario this use-after-free is benign, because 'node_inode' remains partially valid data even after kmem_cache_free(). But things may change if, while 'meta_inode' is evicted in one f2fs filesystem, another (mounted) f2fs filesystem requests inode from cache, and formely 'node_inode' of the first filesystem is returned.
Found by Linux File System Verification project (linuxtesting.org).
-- Best regards,
Andrey Tsyvarev
Linux Verification Center, ISPRAS
web:http://linuxtesting.org
| |