lkml.org 
[lkml]   [2011]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH v3 1/4] exec: introduce get_arg_ptr() helper
    Introduce get_arg_ptr() helper, convert count() and copy_strings()
    to use it.

    No functional changes, preparation. This helper is trivial, it just
    reads the pointer from argv/envp user-space array.

    Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    ---

    fs/exec.c | 36 +++++++++++++++++++++++++-----------
    1 file changed, 25 insertions(+), 11 deletions(-)

    --- 38/fs/exec.c~1_get_arg_ptr 2011-03-02 15:15:27.000000000 +0100
    +++ 38/fs/exec.c 2011-03-02 15:16:44.000000000 +0100
    @@ -395,6 +395,17 @@ err:
    return err;
    }

    +static const char __user *
    +get_arg_ptr(const char __user * const __user *argv, int argc)
    +{
    + const char __user *ptr;
    +
    + if (get_user(ptr, argv + argc))
    + return ERR_PTR(-EFAULT);
    +
    + return ptr;
    +}
    +
    /*
    * count() counts the number of strings in array ARGV.
    */
    @@ -404,13 +415,14 @@ static int count(const char __user * con

    if (argv != NULL) {
    for (;;) {
    - const char __user * p;
    + const char __user *p = get_arg_ptr(argv, i);

    - if (get_user(p, argv))
    - return -EFAULT;
    if (!p)
    break;
    - argv++;
    +
    + if (IS_ERR(p))
    + return -EFAULT;
    +
    if (i++ >= max)
    return -E2BIG;

    @@ -440,16 +452,18 @@ static int copy_strings(int argc, const
    int len;
    unsigned long pos;

    - if (get_user(str, argv+argc) ||
    - !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
    - ret = -EFAULT;
    + ret = -EFAULT;
    + str = get_arg_ptr(argv, argc);
    + if (IS_ERR(str))
    goto out;
    - }

    - if (!valid_arg_len(bprm, len)) {
    - ret = -E2BIG;
    + len = strnlen_user(str, MAX_ARG_STRLEN);
    + if (!len)
    + goto out;
    +
    + ret = -E2BIG;
    + if (!valid_arg_len(bprm, len))
    goto out;
    - }

    /* We're going to work our way backwords. */
    pos = bprm->p;


    \
     
     \ /
      Last update: 2011-03-02 17:39    [W:0.051 / U:65.764 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site