From: Weiming Shi Date: Wed, 10 Jun 2026 22:26:12 +0000 (+0930) Subject: btrfs: tree-checker: validate INODE_REF's namelen X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3dc22abc21f5892406c09202fa2627196cc96967;p=thirdparty%2Fkernel%2Flinux.git btrfs: tree-checker: validate INODE_REF's namelen [BUG] A crafted btrfs image can trigger the following crash: BUG: unable to handle page fault for address: ffffd1dc42884000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page CPU: 9 UID: 0 PID: 1034 Comm: poc Not tainted 7.1.0-rc4-custom+ #383 PREEMPT(full) 46af0a92938a63be7132e0dfd71e62327c51d5c2 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:memcpy+0xc/0x10 Call Trace: read_extent_buffer+0xe4/0x100 [btrfs 3cf0785dd58fec8c5ff84633b772f17ce1f92a8f] btrfs_get_name+0x15e/0x1e0 [btrfs 3cf0785dd58fec8c5ff84633b772f17ce1f92a8f] reconnect_path+0x165/0x390 exportfs_decode_fh_raw+0x337/0x400 ? drop_caches_sysctl_handler+0xb0/0xb0 ---[ end trace 0000000000000000 ]--- RIP: 0010:memcpy+0xc/0x10 Kernel panic - not syncing: Fatal exception [CAUSE] TThe crafted image has the following corrupted INODE_REF item: item 9 key (258 INODE_REF 257) itemoff 11544 itemsize 4106 index 2 namelen 4096 name: d\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000 The itemsize matches the namelen, but the namelen is 4096, way larger than normal name length limit (BTRFS_NAME_LEN, 255). Meanwhile the memory of the @name is only 255 byte sized, this will cause out-of-boundary access, and cause the above crash. [FIX] Add extra namelen verification for INODE_REF, just like what we have done in ROOT_REF checks. Now the crafted image can be rejected gracefully: BTRFS critical (device dm-2): corrupt leaf: root=5 block=30572544 slot=14 ino=259, invalid inode ref name length, has 4096 expect [1, 255] BTRFS error (device dm-2): read time tree block corruption detected on logical 30572544 mirror 2 Reported-by: Xiang Mei Link: https://lore.kernel.org/linux-btrfs/aik0hEV6ehKx6Ldv@Air.local/ Acked-by: Weiming Shi Signed-off-by: Weiming Shi [ Rebase, add a Link: tag, add an simple cause analyze ] Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index cb3e676a81cc..0ce91396b517 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -1923,6 +1923,12 @@ static int check_inode_ref(struct extent_buffer *leaf, iref = (struct btrfs_inode_ref *)ptr; namelen = btrfs_inode_ref_name_len(leaf, iref); + if (unlikely(namelen == 0 || namelen > BTRFS_NAME_LEN)) { + inode_ref_err(leaf, slot, + "invalid inode ref name length, has %u expect [1, %u]", + namelen, BTRFS_NAME_LEN); + return -EUCLEAN; + } if (unlikely(ptr + sizeof(*iref) + namelen > end)) { inode_ref_err(leaf, slot, "inode ref overflow, ptr %lu end %lu namelen %u",