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A maliciously crafted HFS+ image can request the creation of a duplicate bnode (e.g., bnode 0) that is mathematically within the tree->node_count bounds, but has already been hashed in memory. This bypasses initial boundary checks and triggers a WARN_ON(1) upon a duplicate hash collision. This patch adds a clean state check in hfs_bnode_create. If a requested node is already hashed, the driver now safely rejects the operation with -EEXIST instead of tripping the kernel warning. Reported-by: syzbot+f83fa2cf571bd7650422@syzkaller.appspotmail.com Signed-off-by: Sainath Manda sainathmanda777@gmail.com --- fs/hfsplus/bnode.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/hfsplus/bnode.c b/fs/hfsplus/bnode.c index f8b5a8ae5..5946baad2 100644 --- a/fs/hfsplus/bnode.c +++ b/fs/hfsplus/bnode.c @@ -626,12 +626,18 @@ struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num) struct page **pagep; int i; + if (num >= tree->node_count) { + pr_err("hfsplus: attempted to create invalid bnode %u (max %u)\n", + num, tree->node_count); + return ERR_PTR(-EINVAL); + } + spin_lock(&tree->hash_lock); node = hfs_bnode_findhash(tree, num); spin_unlock(&tree->hash_lock); if (node) { - pr_crit("new node %u already hashed?\n", num); - WARN_ON(1); + pr_err("hfsplus: attempted to create already hashed bnode %u\n", + num); return ERR_PTR(-EEXIST); } node = __hfs_bnode_create(tree, num); -- 2.34.1