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    Subject[12/26] KEYS: Fix a NULL pointer deref in the user-defined key type
    3.1-stable review patch.  If anyone has any objections, please let me know.


    From: David Howells <>

    commit 9f35a33b8d06263a165efe3541d9aa0cdbd70b3b upstream.

    Fix a NULL pointer deref in the user-defined key type whereby updating a
    negative key into a fully instantiated key will cause an oops to occur
    when the code attempts to free the non-existent old payload.

    This results in an oops that looks something like the following:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
    IP: [<ffffffff81085fa1>] __call_rcu+0x11/0x13e
    PGD 3391d067 PUD 3894a067 PMD 0
    Oops: 0002 [#1] SMP
    CPU 1
    Pid: 4354, comm: keyctl Not tainted 3.1.0-fsdevel+ #1140 /DG965RY
    RIP: 0010:[<ffffffff81085fa1>] [<ffffffff81085fa1>] __call_rcu+0x11/0x13e
    RSP: 0018:ffff88003d591df8 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000006e
    RDX: ffffffff8161d0c0 RSI: 0000000000000000 RDI: 0000000000000000
    RBP: ffff88003d591e18 R08: 0000000000000000 R09: ffffffff8152fa6c
    R10: 0000000000000000 R11: 0000000000000300 R12: ffff88003b8f9538
    R13: ffffffff8161d0c0 R14: ffff88003b8f9d50 R15: ffff88003c69f908
    FS: 00007f97eb18c720(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000000008 CR3: 000000003d47a000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    Process keyctl (pid: 4354, threadinfo ffff88003d590000, task ffff88003c78a040)
    ffff88003e0ffde0 ffff88003b8f9538 0000000000000001 ffff88003b8f9d50
    ffff88003d591e28 ffffffff810860f0 ffff88003d591e68 ffffffff8117bfea
    ffff88003d591e68 ffffffff00000000 ffff88003e0ffde1 ffff88003e0ffde0
    Call Trace:
    [<ffffffff810860f0>] call_rcu_sched+0x10/0x12
    [<ffffffff8117bfea>] user_update+0x8d/0xa2
    [<ffffffff8117723a>] key_create_or_update+0x236/0x270
    [<ffffffff811789b1>] sys_add_key+0x123/0x17e
    [<ffffffff813b84bb>] system_call_fastpath+0x16/0x1b

    Signed-off-by: David Howells <>
    Acked-by: Jeff Layton <>
    Acked-by: Neil Horman <>
    Acked-by: Steve Dickson <>
    Acked-by: James Morris <>
    Signed-off-by: Linus Torvalds <>
    Signed-off-by: Greg Kroah-Hartman <>

    security/keys/user_defined.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/security/keys/user_defined.c
    +++ b/security/keys/user_defined.c
    @@ -102,7 +102,8 @@ int user_update(struct key *key, const v
    key->expiry = 0;

    - kfree_rcu(zap, rcu);
    + if (zap)
    + kfree_rcu(zap, rcu);

    return ret;

     \ /
      Last update: 2011-11-19 01:17    [W:0.020 / U:11.176 seconds]
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