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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (by Flathub.org) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-09-30 at 20:50 +0200, Mahmut Emin Kurhan wrote: > hfs_btree_open() can fail after hfs_bnode_find(tree, > HFSPLUS_TREE_HEAD) > has already inserted the head node into tree->node_hash. >=20 > __hfs_bnode_create() inserts the new bnode into tree->node_hash > before > it reads the node's pages; if a page read fails it sets > HFS_BNODE_ERROR > and returns the node still hashed. hfs_bnode_find() then takes its > node_error path, which calls hfs_bnode_put(). hfs_bnode_put() only > frees > a node once its refcount reaches zero *and* HFS_BNODE_DELETED is set; > for > the errored head node that flag is not set, so the node stays in > tree->node_hash with a zero refcount. >=20 > hfs_btree_open() then sees IS_ERR(node) and jumps to free_tree:, > which > does a bare kfree(tree). Only hfs_btree_close() walks tree- > >node_hash[] > and frees the cached nodes, so the head node is leaked. Mounting a > crafted HFS+ image whose head B-tree node fails to read therefore > leaks > kernel memory on every attempt. I assume that HFS code requires the same fix. Am I right? >=20 > Reported by kmemleak while fuzzing HFS+ image mounts: >=20 > =C2=A0 BUG: memory leak > =C2=A0 unreferenced object (size 192): > =C2=A0=C2=A0=C2=A0 __hfs_bnode_create+0x105/0x8d0 fs/hfsplus/bnode.c > =C2=A0=C2=A0=C2=A0 hfsplus_bnode_find=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 fs/hfsplus/bnode.c > =C2=A0=C2=A0=C2=A0 hfsplus_btree_open=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 fs/hfsplus/btree.c > =C2=A0=C2=A0=C2=A0 hfsplus_fill_super=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 fs/hfsplus/super.c >=20 > Free any nodes still present in tree->node_hash on the error path > before > freeing the tree. The paths that reach free_tree before > hfs_bnode_find() > have an empty hash, so the loop is a no-op there. >=20 > Found via coverage-guided fuzzing (syzkaller + kmemleak) by Noroxi. >=20 > Signed-off-by: Mahmut Emin Kurhan > --- > =C2=A0fs/hfsplus/btree.c | 18 ++++++++++++++++++ > =C2=A01 file changed, 18 insertions(+) >=20 > diff --git a/fs/hfsplus/btree.c b/fs/hfsplus/btree.c > index 2ea8cd565..3de32f221 100644 > --- a/fs/hfsplus/btree.c > +++ b/fs/hfsplus/btree.c > @@ -403,6 +403,24 @@ struct hfs_btree *hfs_btree_open(struct > super_block *sb, u32 id) > =C2=A0 tree->inode->i_mapping->a_ops =3D &hfsplus_aops; > =C2=A0 iput(tree->inode); > =C2=A0 free_tree: > + /* > + * A B*tree node may already have been inserted into tree- > >node_hash > + * (e.g. an errored head node from hfs_bnode_find()).=C2=A0 Only > + * hfs_btree_close() frees hashed nodes, so a bare > kfree(tree) here > + * leaks them.=C2=A0 Release them before freeing the tree. > + */ > + { I don't like of introducing the brackets here. Let's declare the variables at the beginning of the method. > + int i; > + struct hfs_bnode *node; We already has this declaration [1]. > + > + for (i =3D 0; i < NODE_HASH_SIZE; i++) { > + while ((node =3D tree->node_hash[i])) { > + tree->node_hash[i] =3D node- > >next_hash; > + hfs_bnode_free(node); > + tree->node_hash_cnt--; > + } > + } This logic looks pretty similar to the hfs_btree_close(). Should we introduce a small method that can be reused in both cases? I assume that you are not using the spin_lock(&tree->hash_lock) because the tree creation is not finished and nobody can try to use the tree. Am I right? Thanks, Slava. [1] https://elixir.bootlin.com/linux/v7.3-rc3/source/fs/hfsplus/btree.c#L273 > + } > =C2=A0 kfree(tree); > =C2=A0 return NULL; > =C2=A0} > -- > 2.43.0