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author | 2017-12-08 15:13:29 +0000 | |
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committer | 2017-12-08 15:13:29 +0000 | |
commit | 18026d866801d0c52e5550210563222bd6c7191d (patch) | |
tree | 744c23841e67ff704fa4374b14a05ec542b4f4eb /security/keys | |
parent | security: keys: remove redundant assignment to key_ref (diff) | |
download | linux-18026d866801d0c52e5550210563222bd6c7191d.tar.gz linux-18026d866801d0c52e5550210563222bd6c7191d.tar.bz2 linux-18026d866801d0c52e5550210563222bd6c7191d.zip |
KEYS: reject NULL restriction string when type is specified
keyctl_restrict_keyring() allows through a NULL restriction when the
"type" is non-NULL, which causes a NULL pointer dereference in
asymmetric_lookup_restriction() when it calls strcmp() on the
restriction string.
But no key types actually use a "NULL restriction" to mean anything, so
update keyctl_restrict_keyring() to reject it with EINVAL.
Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: 97d3aa0f3134 ("KEYS: Add a lookup_restriction function for the asymmetric key type")
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'security/keys')
-rw-r--r-- | security/keys/keyctl.c | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 76d22f726ae4..1ffe60bb2845 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1588,9 +1588,8 @@ error_keyring: * The caller must have Setattr permission to change keyring restrictions. * * The requested type name may be a NULL pointer to reject all attempts - * to link to the keyring. If _type is non-NULL, _restriction can be - * NULL or a pointer to a string describing the restriction. If _type is - * NULL, _restriction must also be NULL. + * to link to the keyring. In this case, _restriction must also be NULL. + * Otherwise, both _type and _restriction must be non-NULL. * * Returns 0 if successful. */ @@ -1598,7 +1597,6 @@ long keyctl_restrict_keyring(key_serial_t id, const char __user *_type, const char __user *_restriction) { key_ref_t key_ref; - bool link_reject = !_type; char type[32]; char *restriction = NULL; long ret; @@ -1607,31 +1605,29 @@ long keyctl_restrict_keyring(key_serial_t id, const char __user *_type, if (IS_ERR(key_ref)) return PTR_ERR(key_ref); + ret = -EINVAL; if (_type) { - ret = key_get_type_from_user(type, _type, sizeof(type)); - if (ret < 0) + if (!_restriction) goto error; - } - if (_restriction) { - if (!_type) { - ret = -EINVAL; + ret = key_get_type_from_user(type, _type, sizeof(type)); + if (ret < 0) goto error; - } restriction = strndup_user(_restriction, PAGE_SIZE); if (IS_ERR(restriction)) { ret = PTR_ERR(restriction); goto error; } + } else { + if (_restriction) + goto error; } - ret = keyring_restrict(key_ref, link_reject ? NULL : type, restriction); + ret = keyring_restrict(key_ref, _type ? type : NULL, restriction); kfree(restriction); - error: key_ref_put(key_ref); - return ret; } |