core_pattern: fix truncation by core_pattern handler with long parameters
We met a parameter truncated issue, consider following:
> echo "|/root/core_pattern_pipe_test %p /usr/libexec/blah-blah-blah \
%s %c %p %u %g 11 12345678901234567890123456789012345678 %t" > \
/proc/sys/kernel/core_pattern
This is okay because the strings is less than CORENAME_MAX_SIZE. "cat
/proc/sys/kernel/core_pattern" shows the whole string. but after we run
core_pattern_pipe_test in man page, we found last parameter was truncated
like below:
argc[10]=<12807486>
The root cause is core_pattern allows % specifiers, which need to be
replaced during parse time, but the replace may expand the strings to
larger than CORENAME_MAX_SIZE. So if the last parameter is % specifiers,
the replace code is using snprintf(out_ptr, out_end - out_ptr, ...), this
will write out of corename array.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Neil Horman <nhorman@tuxdriver.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Xiaotian Feng
Linus Torvalds
parent
9b1bf12d5d
commit
1b0d300bd0
155
fs/exec.c
155
fs/exec.c
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@ -66,6 +66,12 @@ char core_pattern[CORENAME_MAX_SIZE] = "core";
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unsigned int core_pipe_limit;
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int suid_dumpable = 0;
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struct core_name {
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char *corename;
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int used, size;
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};
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static atomic_t call_count = ATOMIC_INIT(1);
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/* The maximal length of core_pattern is also specified in sysctl.c */
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static LIST_HEAD(formats);
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@ -1459,127 +1465,148 @@ void set_binfmt(struct linux_binfmt *new)
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EXPORT_SYMBOL(set_binfmt);
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static int expand_corename(struct core_name *cn)
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{
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char *old_corename = cn->corename;
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cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
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cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
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if (!cn->corename) {
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kfree(old_corename);
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return -ENOMEM;
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}
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return 0;
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}
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static int cn_printf(struct core_name *cn, const char *fmt, ...)
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{
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char *cur;
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int need;
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int ret;
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va_list arg;
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va_start(arg, fmt);
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need = vsnprintf(NULL, 0, fmt, arg);
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va_end(arg);
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if (likely(need < cn->size - cn->used - 1))
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goto out_printf;
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ret = expand_corename(cn);
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if (ret)
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goto expand_fail;
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out_printf:
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cur = cn->corename + cn->used;
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va_start(arg, fmt);
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vsnprintf(cur, need + 1, fmt, arg);
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va_end(arg);
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cn->used += need;
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return 0;
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expand_fail:
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return ret;
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}
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/* format_corename will inspect the pattern parameter, and output a
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* name into corename, which must have space for at least
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* CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
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*/
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static int format_corename(char *corename, long signr)
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static int format_corename(struct core_name *cn, long signr)
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{
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const struct cred *cred = current_cred();
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const char *pat_ptr = core_pattern;
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int ispipe = (*pat_ptr == '|');
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char *out_ptr = corename;
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char *const out_end = corename + CORENAME_MAX_SIZE;
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int rc;
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int pid_in_pattern = 0;
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int err = 0;
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cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
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cn->corename = kmalloc(cn->size, GFP_KERNEL);
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cn->used = 0;
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if (!cn->corename)
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return -ENOMEM;
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/* Repeat as long as we have more pattern to process and more output
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space */
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while (*pat_ptr) {
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if (*pat_ptr != '%') {
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if (out_ptr == out_end)
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if (*pat_ptr == 0)
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goto out;
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*out_ptr++ = *pat_ptr++;
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err = cn_printf(cn, "%c", *pat_ptr++);
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} else {
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switch (*++pat_ptr) {
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/* single % at the end, drop that */
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case 0:
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goto out;
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/* Double percent, output one percent */
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case '%':
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if (out_ptr == out_end)
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goto out;
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*out_ptr++ = '%';
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err = cn_printf(cn, "%c", '%');
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break;
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/* pid */
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case 'p':
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pid_in_pattern = 1;
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%d", task_tgid_vnr(current));
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%d",
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task_tgid_vnr(current));
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break;
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/* uid */
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case 'u':
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%d", cred->uid);
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%d", cred->uid);
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break;
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/* gid */
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case 'g':
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%d", cred->gid);
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%d", cred->gid);
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break;
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/* signal that caused the coredump */
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case 's':
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%ld", signr);
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%ld", signr);
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break;
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/* UNIX time of coredump */
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case 't': {
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struct timeval tv;
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do_gettimeofday(&tv);
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%lu", tv.tv_sec);
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%lu", tv.tv_sec);
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break;
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}
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/* hostname */
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case 'h':
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down_read(&uts_sem);
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%s", utsname()->nodename);
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err = cn_printf(cn, "%s",
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utsname()->nodename);
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up_read(&uts_sem);
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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break;
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/* executable */
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case 'e':
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%s", current->comm);
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%s", current->comm);
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break;
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/* core limit size */
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case 'c':
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rc = snprintf(out_ptr, out_end - out_ptr,
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"%lu", rlimit(RLIMIT_CORE));
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, "%lu",
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rlimit(RLIMIT_CORE));
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break;
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default:
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break;
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}
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++pat_ptr;
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}
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if (err)
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return err;
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}
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/* Backward compatibility with core_uses_pid:
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*
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* If core_pattern does not include a %p (as is the default)
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* and core_uses_pid is set, then .%pid will be appended to
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* the filename. Do not do this for piped commands. */
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if (!ispipe && !pid_in_pattern && core_uses_pid) {
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rc = snprintf(out_ptr, out_end - out_ptr,
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".%d", task_tgid_vnr(current));
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if (rc > out_end - out_ptr)
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goto out;
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out_ptr += rc;
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err = cn_printf(cn, ".%d", task_tgid_vnr(current));
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if (err)
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return err;
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}
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out:
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*out_ptr = 0;
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return ispipe;
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}
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@ -1856,7 +1883,7 @@ static int umh_pipe_setup(struct subprocess_info *info)
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void do_coredump(long signr, int exit_code, struct pt_regs *regs)
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{
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struct core_state core_state;
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char corename[CORENAME_MAX_SIZE + 1];
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struct core_name cn;
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struct mm_struct *mm = current->mm;
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struct linux_binfmt * binfmt;
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const struct cred *old_cred;
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@ -1911,7 +1938,13 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
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*/
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clear_thread_flag(TIF_SIGPENDING);
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ispipe = format_corename(corename, signr);
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ispipe = format_corename(&cn, signr);
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if (ispipe == -ENOMEM) {
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printk(KERN_WARNING "format_corename failed\n");
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printk(KERN_WARNING "Aborting core\n");
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goto fail_corename;
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}
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if (ispipe) {
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int dump_count;
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@ -1948,7 +1981,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
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goto fail_dropcount;
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}
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helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
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helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
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if (!helper_argv) {
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printk(KERN_WARNING "%s failed to allocate memory\n",
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__func__);
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@ -1961,7 +1994,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
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argv_free(helper_argv);
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if (retval) {
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printk(KERN_INFO "Core dump to %s pipe failed\n",
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corename);
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cn.corename);
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goto close_fail;
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}
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} else {
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@ -1970,7 +2003,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
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if (cprm.limit < binfmt->min_coredump)
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goto fail_unlock;
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cprm.file = filp_open(corename,
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cprm.file = filp_open(cn.corename,
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O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
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0600);
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if (IS_ERR(cprm.file))
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@ -2012,6 +2045,8 @@ fail_dropcount:
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if (ispipe)
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atomic_dec(&core_dump_count);
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fail_unlock:
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kfree(cn.corename);
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fail_corename:
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coredump_finish(mm);
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revert_creds(old_cred);
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fail_creds:
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