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Subject: Re: KASAN: slab-out-of-bounds Read in ecryptfs_verify_auth_tok_from_key
Author: neganhat@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 58165928ed1e..3baccd4143e8 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -124,6 +124,9 @@ ecryptfs_get_key_payload_data(struct key *key)
        if (!ukp)
                return ERR_PTR(-EKEYREVOKED);

+       if (ukp->datalen < sizeof(struct ecryptfs_auth_tok))
+               return ERR_PTR(-EINVAL);
+
        return (struct ecryptfs_auth_tok *)ukp->data;
 }