From dbf20cb259e879e2d939fd3fd5c792732d845195 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Fri, 25 Jul 2014 12:00:57 +0800 Subject: [PATCH] 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: [] f2fs_evict_inode+0x102/0x2e0 [f2fs] [] evict+0x15f/0x290 [< inlined >] iput+0x196/0x280 iput_final [] iput+0x196/0x280 [] f2fs_put_super+0xd6/0x170 [f2fs] [] generic_shutdown_super+0xc5/0x1b0 [] kill_block_super+0x4d/0xb0 [] deactivate_locked_super+0x66/0x80 [] deactivate_super+0x68/0x80 [] mntput_no_expire+0x198/0x250 [< inlined >] SyS_umount+0xe9/0x1a0 SYSC_umount [] SyS_umount+0xe9/0x1a0 [] system_call_fastpath+0x16/0x1b Freed by thread T3: [] 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 [] rcu_process_callbacks+0x2d6/0x930 [] __do_softirq+0x142/0x380 [] run_ksoftirqd+0x30/0x50 [] smpboot_thread_fn+0x197/0x280 [] kthread+0x148/0x160 [] ret_from_fork+0x7c/0xb0 Allocated by thread T22276: [] f2fs_alloc_inode+0x2d/0x170 [f2fs] [] iget_locked+0x10a/0x230 [] f2fs_iget+0x35/0xa80 [f2fs] [] f2fs_fill_super+0xb53/0xff0 [f2fs] [] mount_bdev+0x1de/0x240 [] f2fs_mount+0x10/0x20 [f2fs] [] mount_fs+0x55/0x220 [] vfs_kern_mount+0x66/0x200 [< inlined >] do_mount+0x2b4/0x1120 do_new_mount [] do_mount+0x2b4/0x1120 [< inlined >] SyS_mount+0xb2/0x110 SYSC_mount [] SyS_mount+0xb2/0x110 [] 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 Tested-by: Andrey Tsyvarev Signed-off-by: Gu Zheng Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/inode.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index 2cf6962f6cc8..cafba3c9f8d8 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); } -- 2.20.1