Origin 'verify_dir_item' verifies name_len of dir_item with fixed values
but no 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] Code: 48 29 c3 74 5f 4c 89 d8 4c 89 d6 48 29 c8 48 39 d8 48 0f 47 c3 49 03 30 48 c1 fe 06 48 c1 e6 0c 4c 01 ce 48 01 ce 83 f8 08 72 b3 <48> 8b 0e 49 83 c0 08 48 89 0a 89 c1 48 8b 7c 0e f8 48 89 7c 0a
[ 48.490008] RIP: read_extent_buffer+0xd2/0x190 [btrfs] RSP: ffffc90004803d98
[ 48.499455] ---[ end trace 321920d8e8339505 ]---
Solve 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@xxxxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 2 +-
fs/btrfs/dir-item.c | 10 +++++++++-
fs/btrfs/inode.c | 2 +-
fs/btrfs/tree-log.c | 4 ++--
fs/btrfs/xattr.c | 2 +-
5 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 776b16ec7a47..98a69c58fe57 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3031,7 +3031,7 @@ 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 b54c920c8412..806b9fe0178a 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)) >
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 17cbe9306faf..df948569c393 100644
--- 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 ccfe9fe7754a..1930f28edcdd 100644
--- 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 @@ static noinline int check_item_in_log(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)) {
ret = -EIO;
goto out;
}
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index b3cbf80c5acf..2c7e53f9ff1b 100644
--- 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;
}
--
2.13.0
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