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    SubjectRe: [Feature Request?] Inline compression of process core dumps
    > Looking at the code, it seems to me that format_corename() is appending 
    > .pid, regardless if !core_uses_pid and corename[0]=='|', in which case
    > it creates an invalid path for call_usermodehelper_pipe().
    >
    > Bug in the code, or bug in my methods?

    This looks somewhat better and might do the trick. Also fixes a very very
    obscure security corner case. If you change core pattern to start with
    the program name then the user can run a program called "|myevilhack" as
    it stands. The patch checks for "|" in the pattern not the output and
    doesn't nail a pid on to a piped name.

    Signed-off-by: Alan Cox <alan@redhat.com>

    diff -u --exclude-from /usr/src/exclude --new-file --recursive linux.vanilla-2.6.21-rc6-mm1/fs/exec.c linux-2.6.21-rc6-mm1/fs/exec.c
    --- linux.vanilla-2.6.21-rc6-mm1/fs/exec.c 2007-04-12 14:15:05.000000000 +0100
    +++ linux-2.6.21-rc6-mm1/fs/exec.c 2007-04-13 13:11:20.709835952 +0100
    @@ -1265,13 +1265,17 @@
    * name into corename, which must have space for at least
    * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
    */
    -static void format_corename(char *corename, const char *pattern, long signr)
    +static int format_corename(char *corename, const char *pattern, long signr)
    {
    const char *pat_ptr = pattern;
    char *out_ptr = corename;
    char *const out_end = corename + CORENAME_MAX_SIZE;
    int rc;
    int pid_in_pattern = 0;
    + int ispipe = 0;
    +
    + if (*pattern == '|')
    + ispipe = 1;

    /* Repeat as long as we have more pattern to process and more output
    space */
    @@ -1362,8 +1366,8 @@
    *
    * If core_pattern does not include a %p (as is the default)
    * and core_uses_pid is set, then .%pid will be appended to
    - * the filename */
    - if (!pid_in_pattern
    + * the filename. Do not do this for piped commands. */
    + if (!ispipe && !pid_in_pattern
    && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
    rc = snprintf(out_ptr, out_end - out_ptr,
    ".%d", current->tgid);
    @@ -1371,8 +1375,9 @@
    goto out;
    out_ptr += rc;
    }
    - out:
    +out:
    *out_ptr = 0;
    + return ispipe;
    }

    static void zap_process(struct task_struct *start)
    @@ -1523,16 +1528,15 @@
    * uses lock_kernel()
    */
    lock_kernel();
    - format_corename(corename, core_pattern, signr);
    + ispipe = format_corename(corename, core_pattern, signr);
    unlock_kernel();
    - if (corename[0] == '|') {
    + if (ispipe) {
    /* SIGPIPE can happen, but it's just never processed */
    if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
    printk(KERN_INFO "Core dump to %s pipe failed\n",
    corename);
    goto fail_unlock;
    }
    - ispipe = 1;
    } else
    file = filp_open(corename,
    O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
    -
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