This is a note to let you know that I've just added the patch titled
btrfs: tree-checker: validate dref root and objectid
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-tree-checker-validate-dref-root-and-objectid.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 33a1450c0335a4cc4ad8ed4d72a5bb2250885acf
Author: Qu Wenruo <wqu@xxxxxxxx>
Date: Mon Jul 15 16:07:07 2024 +0930
btrfs: tree-checker: validate dref root and objectid
[ Upstream commit f333a3c7e8323499aa65038e77fe8f3199d4e283 ]
[CORRUPTION]
There is a bug report that btrfs flips RO due to a corruption in the
extent tree, the involved dumps looks like this:
item 188 key (402811572224 168 4096) itemoff 14598 itemsize 79
extent refs 3 gen 3678544 flags 1
ref#0: extent data backref root 13835058055282163977 objectid 281473384125923 offset 81432576 count 1
ref#1: shared data backref parent 1947073626112 count 1
ref#2: shared data backref parent 1156030103552 count 1
BTRFS critical (device vdc1: state EA): unable to find ref byte nr 402811572224 parent 0 root 265 owner 28703026 offset 81432576 slot 189
BTRFS error (device vdc1: state EA): failed to run delayed ref for logical 402811572224 num_bytes 4096 type 178 action 2 ref_mod 1: -2
[CAUSE]
The corrupted entry is ref#0 of item 188.
The root number 13835058055282163977 is beyond the upper limit for root
items (the current limit is 1 << 48), and the objectid also looks
suspicious.
Only the offset and count is correct.
[ENHANCEMENT]
Although it's still unknown why we have such many bytes corrupted
randomly, we can still enhance the tree-checker for data backrefs by:
- Validate the root value
For now there should only be 3 types of roots can have data backref:
* subvolume trees
* data reloc trees
* root tree
Only for v1 space cache
- validate the objectid value
The objectid should be a valid inode number.
Hopefully we can catch such problem in the future with the new checkers.
Reported-by: Kai Krakow <hurikhan77@xxxxxxxxx>
Link: https://lore.kernel.org/linux-btrfs/CAMthOuPjg5RDT-G_LXeBBUUtzt3cq=JywF+D1_h+JYxe=WKp-Q@xxxxxxxxxxxxxx/#t
Reviewed-by: Filipe Manana <fdmanana@xxxxxxxx>
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 7ff61909648d7..46c1f74983956 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -1266,6 +1266,19 @@ static void extent_err(const struct extent_buffer *eb, int slot,
va_end(args);
}
+static bool is_valid_dref_root(u64 rootid)
+{
+ /*
+ * The following tree root objectids are allowed to have a data backref:
+ * - subvolume trees
+ * - data reloc tree
+ * - tree root
+ * For v1 space cache
+ */
+ return is_fstree(rootid) || rootid == BTRFS_DATA_RELOC_TREE_OBJECTID ||
+ rootid == BTRFS_ROOT_TREE_OBJECTID;
+}
+
static int check_extent_item(struct extent_buffer *leaf,
struct btrfs_key *key, int slot,
struct btrfs_key *prev_key)
@@ -1418,6 +1431,8 @@ static int check_extent_item(struct extent_buffer *leaf,
struct btrfs_extent_data_ref *dref;
struct btrfs_shared_data_ref *sref;
u64 seq;
+ u64 dref_root;
+ u64 dref_objectid;
u64 dref_offset;
u64 inline_offset;
u8 inline_type;
@@ -1461,11 +1476,26 @@ static int check_extent_item(struct extent_buffer *leaf,
*/
case BTRFS_EXTENT_DATA_REF_KEY:
dref = (struct btrfs_extent_data_ref *)(&iref->offset);
+ dref_root = btrfs_extent_data_ref_root(leaf, dref);
+ dref_objectid = btrfs_extent_data_ref_objectid(leaf, dref);
dref_offset = btrfs_extent_data_ref_offset(leaf, dref);
seq = hash_extent_data_ref(
btrfs_extent_data_ref_root(leaf, dref),
btrfs_extent_data_ref_objectid(leaf, dref),
btrfs_extent_data_ref_offset(leaf, dref));
+ if (unlikely(!is_valid_dref_root(dref_root))) {
+ extent_err(leaf, slot,
+ "invalid data ref root value %llu",
+ dref_root);
+ return -EUCLEAN;
+ }
+ if (unlikely(dref_objectid < BTRFS_FIRST_FREE_OBJECTID ||
+ dref_objectid > BTRFS_LAST_FREE_OBJECTID)) {
+ extent_err(leaf, slot,
+ "invalid data ref objectid value %llu",
+ dref_root);
+ return -EUCLEAN;
+ }
if (unlikely(!IS_ALIGNED(dref_offset,
fs_info->sectorsize))) {
extent_err(leaf, slot,
@@ -1601,6 +1631,8 @@ static int check_extent_data_ref(struct extent_buffer *leaf,
return -EUCLEAN;
}
for (; ptr < end; ptr += sizeof(*dref)) {
+ u64 root;
+ u64 objectid;
u64 offset;
/*
@@ -1608,7 +1640,22 @@ static int check_extent_data_ref(struct extent_buffer *leaf,
* overflow from the leaf due to hash collisions.
*/
dref = (struct btrfs_extent_data_ref *)ptr;
+ root = btrfs_extent_data_ref_root(leaf, dref);
+ objectid = btrfs_extent_data_ref_objectid(leaf, dref);
offset = btrfs_extent_data_ref_offset(leaf, dref);
+ if (unlikely(!is_valid_dref_root(root))) {
+ extent_err(leaf, slot,
+ "invalid extent data backref root value %llu",
+ root);
+ return -EUCLEAN;
+ }
+ if (unlikely(objectid < BTRFS_FIRST_FREE_OBJECTID ||
+ objectid > BTRFS_LAST_FREE_OBJECTID)) {
+ extent_err(leaf, slot,
+ "invalid extent data backref objectid value %llu",
+ root);
+ return -EUCLEAN;
+ }
if (unlikely(!IS_ALIGNED(offset, leaf->fs_info->sectorsize))) {
extent_err(leaf, slot,
"invalid extent data backref offset, have %llu expect aligned to %u",
