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    Subject[PATCH - BUGFIX] Smack: Check for 'struct socket' with NULL sk
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    On Mon, Feb 11, 2008 at 07:26:02PM +0100, Joerg Platte wrote:
    > Hi,
    >
    > when booting linux 2.6.25-rc1 I get the following error:
    >
    > BUG: unable to handle kernel NULL pointer dereference at 00000138
    > IP: [<c01aa59e>] smack_netlabel+0x13/0xc8
    > *pde = 00000000
    > Oops: 0000 [#1] PREEMPT
    > Modules linked in: nfsd
    [...]
    > Call Trace:
    > [<c01aacf8>] ? new_inode_smack+0x39/0x3f
    > [<c01aad52>] ? smack_inode_alloc_security+0x16/0x27
    > [<c01a7510>] ? security_inode_alloc+0x19/0x1b
    > [<c01aa665>] ? smack_socket_post_create+0x12/0x18
    > [<c01a7a06>] ? security_socket_post_create+0x16/0x1b
    > [<c02116ce>] ? sock_create_lite+0x44/0x64
    > [<c0211712>] ? kernel_accept+0x24/0x5f

    Hi Joerg,

    There's a small problem with smack and NFS. A similar report was also
    sent here: http://lkml.org/lkml/2007/10/27/85

    Could you please check below patch ? I think it should fix your problem.

    I've also added similar checks in inode_{get/set}security(). Cheating
    from SELinux post_create_socket(), it does the same. Casey, Thoughts ?

    Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
    ---
    diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
    index 1c11e42..eb04278 100644
    --- a/security/smack/smack_lsm.c
    +++ b/security/smack/smack_lsm.c
    @@ -701,7 +701,7 @@ static int smack_inode_getsecurity(const struct inode *inode,
    return -EOPNOTSUPP;

    sock = SOCKET_I(ip);
    - if (sock == NULL)
    + if (sock == NULL || sock->sk == NULL)
    return -EOPNOTSUPP;

    ssp = sock->sk->sk_security;
    @@ -1280,10 +1280,12 @@ static void smack_to_secattr(char *smack, struct netlbl_lsm_secattr *nlsp)
    */
    static int smack_netlabel(struct sock *sk)
    {
    - struct socket_smack *ssp = sk->sk_security;
    + struct socket_smack *ssp;
    struct netlbl_lsm_secattr secattr;
    int rc = 0;

    + BUG_ON(sk == NULL);
    + ssp = sk->sk_security;
    netlbl_secattr_init(&secattr);
    smack_to_secattr(ssp->smk_out, &secattr);
    if (secattr.flags != NETLBL_SECATTR_NONE)
    @@ -1331,7 +1333,7 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
    return -EOPNOTSUPP;

    sock = SOCKET_I(inode);
    - if (sock == NULL)
    + if (sock == NULL || sock->sk == NULL)
    return -EOPNOTSUPP;

    ssp = sock->sk->sk_security;
    @@ -1362,7 +1364,7 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
    static int smack_socket_post_create(struct socket *sock, int family,
    int type, int protocol, int kern)
    {
    - if (family != PF_INET)
    + if (family != PF_INET || sock->sk == NULL)
    return 0;
    /*
    * Set the outbound netlbl.

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      Last update: 2008-02-12 00:29    [W:0.046 / U:59.892 seconds]
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