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    Subject[34-longterm 040/196] netfilter: ipt_CLUSTERIP: fix buffer overflow
    Date
    From: Vasiliy Kulikov <segoon@openwall.com>

    -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
    -------------------

    commit 961ed183a9fd080cf306c659b8736007e44065a5 upstream.

    'buffer' string is copied from userspace. It is not checked whether it is
    zero terminated. This may lead to overflow inside of simple_strtoul().
    Changli Gao suggested to copy not more than user supplied 'size' bytes.

    It was introduced before the git epoch. Files "ipt_CLUSTERIP/*" are
    root writable only by default, however, on some setups permissions might be
    relaxed to e.g. network admin user.

    Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
    Acked-by: Changli Gao <xiaosuo@gmail.com>
    Signed-off-by: Patrick McHardy <kaber@trash.net>
    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    net/ipv4/netfilter/ipt_CLUSTERIP.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
    index ab82840..e8bd977 100644
    --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
    +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
    @@ -663,8 +663,11 @@ static ssize_t clusterip_proc_write(struct file *file, const char __user *input,
    char buffer[PROC_WRITELEN+1];
    unsigned long nodenum;

    - if (copy_from_user(buffer, input, PROC_WRITELEN))
    + if (size > PROC_WRITELEN)
    + return -EIO;
    + if (copy_from_user(buffer, input, size))
    return -EFAULT;
    + buffer[size] = 0;

    if (*buffer == '+') {
    nodenum = simple_strtoul(buffer+1, NULL, 10);
    --
    1.7.9.3


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