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authorChao Yu <chao2.yu@samsung.com>2014-07-25 12:00:57 +0800
committerJaegeuk Kim <jaegeuk@kernel.org>2014-07-25 08:19:55 -0700
commitdbf20cb259e879e2d939fd3fd5c792732d845195 (patch)
treef1d473af67927779a20ea7c78981c4ecaa28bb17
parent32f9bc25cbda00410e2379c58ae027e88bf24770 (diff)
f2fs: avoid use invalid mapping of node_inode when evict meta inode
Andrey Tsyvarev reported: "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] [<ffffffff812359af>] evict+0x15f/0x290 [< inlined >] iput+0x196/0x280 iput_final [<ffffffff812369a6>] iput+0x196/0x280 [<ffffffffa02dc416>] f2fs_put_super+0xd6/0x170 [f2fs] [<ffffffff81210095>] generic_shutdown_super+0xc5/0x1b0 [<ffffffff812105fd>] kill_block_super+0x4d/0xb0 [<ffffffff81210a86>] deactivate_locked_super+0x66/0x80 [<ffffffff81211c98>] deactivate_super+0x68/0x80 [<ffffffff8123cc88>] mntput_no_expire+0x198/0x250 [< inlined >] SyS_umount+0xe9/0x1a0 SYSC_umount [<ffffffff8123f1c9>] SyS_umount+0xe9/0x1a0 [<ffffffff81cc8df9>] system_call_fastpath+0x16/0x1b Freed by thread T3: [<ffffffffa02dc337>] f2fs_i_callback+0x27/0x30 [f2fs] [< inlined >] rcu_process_callbacks+0x2d6/0x930 __rcu_reclaim [< inlined >] rcu_process_callbacks+0x2d6/0x930 rcu_do_batch [< inlined >] rcu_process_callbacks+0x2d6/0x930 invoke_rcu_callbacks [< inlined >] rcu_process_callbacks+0x2d6/0x930 __rcu_process_callbacks [<ffffffff810fd266>] rcu_process_callbacks+0x2d6/0x930 [<ffffffff8107cce2>] __do_softirq+0x142/0x380 [<ffffffff8107cf50>] run_ksoftirqd+0x30/0x50 [<ffffffff810b2a87>] smpboot_thread_fn+0x197/0x280 [<ffffffff810a8238>] kthread+0x148/0x160 [<ffffffff81cc8d4c>] ret_from_fork+0x7c/0xb0 Allocated by thread T22276: [<ffffffffa02dc7dd>] f2fs_alloc_inode+0x2d/0x170 [f2fs] [<ffffffff81235e2a>] iget_locked+0x10a/0x230 [<ffffffffa02d7495>] f2fs_iget+0x35/0xa80 [f2fs] [<ffffffffa02e2393>] f2fs_fill_super+0xb53/0xff0 [f2fs] [<ffffffff81211bce>] mount_bdev+0x1de/0x240 [<ffffffffa02dbce0>] f2fs_mount+0x10/0x20 [f2fs] [<ffffffff81212a85>] mount_fs+0x55/0x220 [<ffffffff8123c026>] vfs_kern_mount+0x66/0x200 [< inlined >] do_mount+0x2b4/0x1120 do_new_mount [<ffffffff812400d4>] do_mount+0x2b4/0x1120 [< inlined >] SyS_mount+0xb2/0x110 SYSC_mount [<ffffffff812414a2>] SyS_mount+0xb2/0x110 [<ffffffff81cc8df9>] system_call_fastpath+0x16/0x1b 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." Nids for both meta_inode and node_inode are reservation, so it's not necessary for us to invalidate pages which will never be allocated. To fix this issue, let's skipping needlessly invalidating pages for {meta,node}_inode in f2fs_evict_inode. Reported-by: Andrey Tsyvarev <tsyvarev@ispras.ru> Tested-by: Andrey Tsyvarev <tsyvarev@ispras.ru> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
-rw-r--r--fs/f2fs/inode.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 2cf6962..cafba3c 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -273,7 +273,7 @@ void f2fs_evict_inode(struct inode *inode)
if (inode->i_ino == F2FS_NODE_INO(sbi) ||
inode->i_ino == F2FS_META_INO(sbi))
- goto no_delete;
+ goto out_clear;
f2fs_bug_on(get_dirty_dents(inode));
remove_dirty_dir_inode(inode);
@@ -295,6 +295,7 @@ void f2fs_evict_inode(struct inode *inode)
sb_end_intwrite(inode->i_sb);
no_delete:
- clear_inode(inode);
invalidate_mapping_pages(NODE_MAPPING(sbi), inode->i_ino, inode->i_ino);
+out_clear:
+ clear_inode(inode);
}