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>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d182ce792173134b91e5e311a681a72249397fb0..5e33e1d6d5c93b5700df62863ff2725a70a40339 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3036,7 +3036,7 @@ struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
                                          const char *name, u16 name_len,
                                          int mod);
 int verify_dir_item(struct btrfs_fs_info *fs_info,
-                   struct extent_buffer *leaf,
+                   struct extent_buffer *leaf, int slot,
                    struct btrfs_dir_item *dir_item);
 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
                                                 struct btrfs_path *path,

diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 5b6c6fb7c80080c5447264fc013b3970e24ac37f..d9c4a3dd071e2d8d93c191f076e72ceadfa99659 100644 (file)
--- 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)) >

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e837713d0d050f9187338cd4430386061d1725ac..86cac431864be77f31e6feb85efb295f77005e7f 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5934,7 +5934,7 @@ static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
                ctx->pos = found_key.offset;
 
                di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
-               if (verify_dir_item(fs_info, leaf, di))
+               if (verify_dir_item(fs_info, leaf, slot, di))
                        goto next;
 
                name_len = btrfs_dir_name_len(leaf, di);

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index ccfe9fe7754a8d4d80fd3e5b1f0a1d2f2118e4e6..1930f28edcdde4572ec998f7aa4f13bd026aeea7 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1841,7 +1841,7 @@ static noinline int replay_one_dir_item(struct btrfs_trans_handle *trans,
        ptr_end = ptr + item_size;
        while (ptr < ptr_end) {
                di = (struct btrfs_dir_item *)ptr;
-               if (verify_dir_item(fs_info, eb, di))
+               if (verify_dir_item(fs_info, eb, slot, di))
                        return -EIO;
                name_len = btrfs_dir_name_len(eb, di);
                ret = replay_one_name(trans, root, path, eb, di, key);
@@ -2017,7 +2017,7 @@ again:
        ptr_end = ptr + item_size;
        while (ptr < ptr_end) {
                di = (struct btrfs_dir_item *)ptr;
-               if (verify_dir_item(fs_info, eb, di)) {
+               if (verify_dir_item(fs_info, eb, slot, di)) {
                        ret = -EIO;
                        goto out;
                }

diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index b3cbf80c5acfa2ebe0541f14d60278f477664908..2c7e53f9ff1b9d3d3c80d6ae5f8b6fcc9e83ec6f 100644 (file)
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -336,7 +336,7 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
                        u32 this_len = sizeof(*di) + name_len + data_len;
                        unsigned long name_ptr = (unsigned long)(di + 1);
 
-                       if (verify_dir_item(fs_info, leaf, di)) {
+                       if (verify_dir_item(fs_info, leaf, slot, di)) {
                                ret = -EIO;
                                goto err;
                        }