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| author | Su Yue <suy.fnst@cn.fujitsu.com> | 2017-06-06 11:57:01 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2017-06-21 19:16:04 +0200 |
| commit | e79a33270d05f711e985b9524a392fd45ad3e93f (patch) | |
| tree | 0d8eb585b167069aebee50b1363c87e0db89e3f7 /fs/btrfs/dir-item.c | |
| parent | btrfs: Introduce btrfs_is_name_len_valid to avoid reading beyond boundary (diff) | |
| download | linux-e79a33270d05f711e985b9524a392fd45ad3e93f.tar.xz linux-e79a33270d05f711e985b9524a392fd45ad3e93f.zip | |
btrfs: Check name_len with boundary in verify dir_item
Originally, verify_dir_item verifies name_len of dir_item with fixed
values but not item boundary.
If corrupted name_len was not bigger than the fixed value, for example
255, the function will think the dir_item is fine. And then reading
beyond boundary will cause crash.
Example:
1. Corrupt one dir_item name_len to be 255.
2. Run 'ls -lar /mnt/test/ > /dev/null'
dmesg:
[ 48.451449] BTRFS info (device vdb1): disk space caching is enabled
[ 48.451453] BTRFS info (device vdb1): has skinny extents
[ 48.489420] general protection fault: 0000 [#1] SMP
[ 48.489571] Modules linked in: ext4 jbd2 mbcache btrfs xor raid6_pq
[ 48.489716] CPU: 1 PID: 2710 Comm: ls Not tainted 4.10.0-rc1 #5
[ 48.489853] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
[ 48.490008] task: ffff880035df1bc0 task.stack: ffffc90004800000
[ 48.490008] RIP: 0010:read_extent_buffer+0xd2/0x190 [btrfs]
[ 48.490008] RSP: 0018:ffffc90004803d98 EFLAGS: 00010202
[ 48.490008] RAX: 000000000000001b RBX: 000000000000001b RCX: 0000000000000000
[ 48.490008] RDX: ffff880079dbf36c RSI: 0005080000000000 RDI: ffff880079dbf368
[ 48.490008] RBP: ffffc90004803dc8 R08: ffff880078e8cc48 R09: ffff880000000000
[ 48.490008] R10: 0000160000000000 R11: 0000000000001000 R12: ffff880079dbf288
[ 48.490008] R13: ffff880078e8ca88 R14: 0000000000000003 R15: ffffc90004803e20
[ 48.490008] FS: 00007fef50c60800(0000) GS:ffff88007d400000(0000) knlGS:0000000000000000
[ 48.490008] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 48.490008] CR2: 000055f335ac2ff8 CR3: 000000007356d000 CR4: 00000000001406e0
[ 48.490008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 48.490008] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 48.490008] Call Trace:
[ 48.490008] btrfs_real_readdir+0x3b7/0x4a0 [btrfs]
[ 48.490008] iterate_dir+0x181/0x1b0
[ 48.490008] SyS_getdents+0xa7/0x150
[ 48.490008] ? fillonedir+0x150/0x150
[ 48.490008] entry_SYSCALL_64_fastpath+0x18/0xad
[ 48.490008] RIP: 0033:0x7fef5032546b
[ 48.490008] RSP: 002b:00007ffeafcdb830 EFLAGS: 00000206 ORIG_RAX: 000000000000004e
[ 48.490008] RAX: ffffffffffffffda RBX: 00007fef5061db38 RCX: 00007fef5032546b
[ 48.490008] RDX: 0000000000008000 RSI: 000055f335abaff0 RDI: 0000000000000003
[ 48.490008] RBP: 00007fef5061dae0 R08: 00007fef5061db48 R09: 0000000000000000
[ 48.490008] R10: 000055f335abafc0 R11: 0000000000000206 R12: 00007fef5061db38
[ 48.490008] R13: 0000000000008040 R14: 00007fef5061db38 R15: 000000000000270e
[ 48.490008] RIP: read_extent_buffer+0xd2/0x190 [btrfs] RSP: ffffc90004803d98
[ 48.499455] ---[ end trace 321920d8e8339505 ]---
Fix it by adding a parameter @slot and check name_len with item boundary
by calling btrfs_is_name_len_valid.
Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
rev
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/dir-item.c')
| -rw-r--r-- | fs/btrfs/dir-item.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c index 5b6c6fb7c800..d9c4a3dd071e 100644 --- a/fs/btrfs/dir-item.c +++ b/fs/btrfs/dir-item.c @@ -395,7 +395,7 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info, leaf = path->nodes[0]; dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item); - if (verify_dir_item(fs_info, leaf, dir_item)) + if (verify_dir_item(fs_info, leaf, path->slots[0], dir_item)) return NULL; total_len = btrfs_item_size_nr(leaf, path->slots[0]); @@ -453,9 +453,11 @@ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans, int verify_dir_item(struct btrfs_fs_info *fs_info, struct extent_buffer *leaf, + int slot, struct btrfs_dir_item *dir_item) { u16 namelen = BTRFS_NAME_LEN; + int ret; u8 type = btrfs_dir_type(leaf, dir_item); if (type >= BTRFS_FT_MAX) { @@ -472,6 +474,12 @@ int verify_dir_item(struct btrfs_fs_info *fs_info, return 1; } + namelen = btrfs_dir_name_len(leaf, dir_item); + ret = btrfs_is_name_len_valid(leaf, slot, + (unsigned long)(dir_item + 1), namelen); + if (!ret) + return 1; + /* BTRFS_MAX_XATTR_SIZE is the same for all dir items */ if ((btrfs_dir_data_len(leaf, dir_item) + btrfs_dir_name_len(leaf, dir_item)) > |