NFS: reject request for id_legacy key without auxdata
commit49686cbbb3
upstream. nfs_idmap_legacy_upcall() is supposed to be called with 'aux' pointing to a 'struct idmap', via the call to request_key_with_auxdata() in nfs_idmap_request_key(). However it can also be reached via the request_key() system call in which case 'aux' will be NULL, causing a NULL pointer dereference in nfs_idmap_prepare_pipe_upcall(), assuming that the key description is valid enough to get that far. Fix this by making nfs_idmap_legacy_upcall() negate the key if no auxdata is provided. As usual, this bug was found by syzkaller. A simple reproducer using the command-line keyctl program is: keyctl request2 id_legacy uid:0 '' @s Fixes:57e62324e4
("NFS: Store the legacy idmapper result in the keyring") Reported-by: syzbot+5dfdbcf7b3eb5912abbb@syzkaller.appspotmail.com Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Trond Myklebust <trondmy@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -568,9 +568,13 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
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struct idmap_msg *im;
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struct idmap *idmap = (struct idmap *)aux;
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struct key *key = cons->key;
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int ret = -ENOMEM;
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int ret = -ENOKEY;
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if (!aux)
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goto out1;
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/* msg and im are freed in idmap_pipe_destroy_msg */
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ret = -ENOMEM;
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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goto out1;
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