[lkml]   [2009]   [Jun]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH 2/2] tracing/filters: use strcmp() instead of strncmp()
    >>>> I don't think there's any security issue. It's irrelevant how big the user-input
    >>>> strings are. The point is those strings are guaranteed to be NULL-terminated.
    >>>> Am I missing something?
    >>>> And I don't think it's necessary to make 2 patches that each patch converts
    >>>> one strncmp to strcmp. But maybe it's better to improve this changelog?
    >>> Hmm, you must be right, indeed they seem to be guaranted beeing NULL-terminated
    >>> strings.
    >> Sorry, I was wrong. :(
    >> Though the user-input strings are guaranted to be NULL-terminated, strings
    >> generated by TRACE_EVENT might not.
    >> We define static strings this way:
    >> TP_struct(
    >> __array(char, foo, LEN)
    >> )
    >> But foo is not necessarily a string, though I doubt someone will use it
    >> as non-string char array.
    > Yeah, but the user defined comparison operand is NULL terminated.
    > So the strcmp will stop at this boundary.

    The user input string is NULL terminated and is limited to MAX_FILTER_STR_VAL,
    and it's strcmp() not strcpy(), but it's still unsafe. No?

    cmp = strcmp(addr, pred->str_val);

    If addr is not NULL-terminated string but char array, and length of
    str_val > length of addr, then we'll be exceeding the boundary of the

    >> Dynamic string is fine, because assign_str() makes it NULL-terminated.
    >> So we can use strcmp() for dynamic strings, but we'd better use strncmp() for
    >> static string.

     \ /
      Last update: 2009-06-01 07:47    [W:0.036 / U:8.976 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site