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 <[email protected]>
Tested-by: Andrey Tsyvarev <[email protected]>
Signed-off-by: Gu Zheng <[email protected]>
Signed-off-by: Chao Yu <[email protected]>
---
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 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);
}
--
2.0.1.474.g72c7794