[PATCH] Don't leak a key reference if request_key() tries to use a revoked keyring

[PATCH] Don't leak a key reference if request_key() tries to use a revoked keyring

[David Jeffery]

If a request_key() call to allocate and fill out a key attempts to insert the
key structure into a revoked keyring, the key will leak, using memory and part
of the user's key quota until the system reboots. This is from a failure of
construct_alloc_key() to decrement the key's reference count after the attempt
to insert into the requested keyring is rejected.

key_put() needs to be called in the link_prealloc_failed callpath to ensure
the unused key is released.

Signed-off-by: David Jeffery <djeffery@redhat.com>

---

The basic way to trigger this is to use keyctl to revoke a session's keyring,
then do an action which will trigger request_key().  request_key() will fail
and a key will leak.


diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 0c7aea4..486ef6f 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -414,6 +414,7 @@ link_check_failed:
 
 link_prealloc_failed:
 	mutex_unlock(&user->cons_lock);
+	key_put(key);
 	kleave(" = %d [prelink]", ret);
 	return ret;
 

Re: [PATCH] Don't leak a key reference if request_key() tries to use a revoked keyring

[David Howells]

David Jeffery <djeffery@redhat.com> wrote:

> If a request_key() call to allocate and fill out a key attempts to insert the
> key structure into a revoked keyring, the key will leak, using memory and part
> of the user's key quota until the system reboots. This is from a failure of
> construct_alloc_key() to decrement the key's reference count after the attempt
> to insert into the requested keyring is rejected.
> 
> key_put() needs to be called in the link_prealloc_failed callpath to ensure
> the unused key is released.

Applied.

[PATCH] Don't leak a key reference if request_key() tries to use a revoked keyring

[David Howells]

From: David Jeffery <djeffery@redhat.com>

If a request_key() call to allocate and fill out a key attempts to insert the
key structure into a revoked keyring, the key will leak, using memory and part
of the user's key quota until the system reboots. This is from a failure of
construct_alloc_key() to decrement the key's reference count after the attempt
to insert into the requested keyring is rejected.

key_put() needs to be called in the link_prealloc_failed callpath to ensure
the unused key is released.

Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 security/keys/request_key.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 0c7aea4dea54..486ef6fa393b 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -414,6 +414,7 @@ link_check_failed:
 
 link_prealloc_failed:
 	mutex_unlock(&user->cons_lock);
+	key_put(key);
 	kleave(" = %d [prelink]", ret);
 	return ret;
 

Re: [PATCH] Don't leak a key reference if request_key() tries to use a revoked keyring

[James Morris]

On Thu, 12 Feb 2015, David Howells wrote:

> From: David Jeffery <djeffery@redhat.com>
> 
> If a request_key() call to allocate and fill out a key attempts to insert the
> key structure into a revoked keyring, the key will leak, using memory and part
> of the user's key quota until the system reboots. This is from a failure of
> construct_alloc_key() to decrement the key's reference count after the attempt
> to insert into the requested keyring is rejected.
> 
> key_put() needs to be called in the link_prealloc_failed callpath to ensure
> the unused key is released.
> 
> Signed-off-by: David Jeffery <djeffery@redhat.com>
> Signed-off-by: David Howells <dhowells@redhat.com>

Applied.


-- 
James Morris
<jmorris@namei.org>