Commit 5649645d authored by Eric Biggers's avatar Eric Biggers Committed by James Morris

KEYS: fix dereferencing NULL payload with nonzero length

sys_add_key() and the KEYCTL_UPDATE operation of sys_keyctl() allowed a
NULL payload with nonzero length to be passed to the key type's
->preparse(), ->instantiate(), and/or ->update() methods.  Various key
types including asymmetric, cifs.idmap, cifs.spnego, and pkcs7_test did
not handle this case, allowing an unprivileged user to trivially cause a
NULL pointer dereference (kernel oops) if one of these key types was
present.  Fix it by doing the copy_from_user() when 'plen' is nonzero
rather than when '_payload' is non-NULL, causing the syscall to fail
with EFAULT as expected when an invalid buffer is specified.

Cc: stable@vger.kernel.org # 2.6.10+
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarJames Morris <james.l.morris@oracle.com>
parent 0f534e4a
...@@ -99,7 +99,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, ...@@ -99,7 +99,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type,
/* pull the payload in if one was supplied */ /* pull the payload in if one was supplied */
payload = NULL; payload = NULL;
if (_payload) { if (plen) {
ret = -ENOMEM; ret = -ENOMEM;
payload = kvmalloc(plen, GFP_KERNEL); payload = kvmalloc(plen, GFP_KERNEL);
if (!payload) if (!payload)
...@@ -324,7 +324,7 @@ long keyctl_update_key(key_serial_t id, ...@@ -324,7 +324,7 @@ long keyctl_update_key(key_serial_t id,
/* pull the payload in if one was supplied */ /* pull the payload in if one was supplied */
payload = NULL; payload = NULL;
if (_payload) { if (plen) {
ret = -ENOMEM; ret = -ENOMEM;
payload = kmalloc(plen, GFP_KERNEL); payload = kmalloc(plen, GFP_KERNEL);
if (!payload) if (!payload)
......
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