From e79a33270d05f711e985b9524a392fd45ad3e93f Mon Sep 17 00:00:00 2001 From: Su Yue Date: Tue, 6 Jun 2017 17:57:01 +0800 Subject: 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 rev Signed-off-by: David Sterba --- fs/btrfs/dir-item.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/dir-item.c') 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)) > -- cgit v1.2.3