lkml.org 
[lkml]   [2010]   [Apr]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v2.6.34-rc5 07/12] KEYS: Fix an RCU warning in the reading of user keys
    Date
    From: David Howells <dhowells@redhat.com>

    Fix an RCU warning in the reading of user keys:

    ===================================================
    [ INFO: suspicious rcu_dereference_check() usage. ]
    ---------------------------------------------------
    security/keys/user_defined.c:202 invoked rcu_dereference_check() without protection!

    other info that might help us debug this:

    rcu_scheduler_active = 1, debug_locks = 0
    1 lock held by keyctl/3637:
    #0: (&key->sem){+++++.}, at: [<ffffffff811a80ae>] keyctl_read_key+0x9c/0xcf

    stack backtrace:
    Pid: 3637, comm: keyctl Not tainted 2.6.34-rc5-cachefs #18
    Call Trace:
    [<ffffffff81051f6c>] lockdep_rcu_dereference+0xaa/0xb2
    [<ffffffff811aa55f>] user_read+0x47/0x91
    [<ffffffff811a80be>] keyctl_read_key+0xac/0xcf
    [<ffffffff811a8a06>] sys_keyctl+0x75/0xb7
    [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b

    Signed-off-by: David Howells <dhowells@redhat.com>
    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    ---
    security/keys/user_defined.c | 3 ++-
    1 files changed, 2 insertions(+), 1 deletions(-)

    diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c
    index 7c687d5..e9aa079 100644
    --- a/security/keys/user_defined.c
    +++ b/security/keys/user_defined.c
    @@ -199,7 +199,8 @@ long user_read(const struct key *key, char __user *buffer, size_t buflen)
    struct user_key_payload *upayload;
    long ret;

    - upayload = rcu_dereference(key->payload.data);
    + upayload = rcu_dereference_protected(
    + key->payload.data, rwsem_is_locked(&((struct key *)key)->sem));
    ret = upayload->datalen;

    /* we can return the data as is */
    --
    1.7.0


    \
     
     \ /
      Last update: 2010-04-23 21:47    [W:0.020 / U:61.664 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site