The patch titled
Subject: argv_split(): teach it to handle mutable strings
has been added to the -mm tree. Its filename is
argv_split-teach-it-to-handle-mutable-strings.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: argv_split(): teach it to handle mutable strings
argv_split() allocates argv[count_argc(str)] array and assumes that it
will find the same number of arguments later. This is obviously wrong if
this string can be changed, say, by sysctl.
With this patch argv_split() kstrndup's the whole string and does not
split it, we simply replace the spaces with zeroes and keep the allocated
memory in argv[-1] for argv_free(arg).
We do not use argv[0] because:
- str can be all-spaces or empty. In fact this case is fine,
we could kfree() it before return, but:
- str can have a space at the start, and we can not rely on
kstrndup(skip_spaces(str)) because it can equally race if
this string is mutable.
Also, simplify count_argc() and kill the no longer used skip_arg().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/argv_split.c | 83 +++++++++++++++++++--------------------------
1 file changed, 36 insertions(+), 47 deletions(-)
diff -puN lib/argv_split.c~argv_split-teach-it-to-handle-mutable-strings lib/argv_split.c
--- a/lib/argv_split.c~argv_split-teach-it-to-handle-mutable-strings
+++ a/lib/argv_split.c
@@ -8,23 +8,17 @@
#include <linux/slab.h>
#include <linux/export.h>
-static const char *skip_arg(const char *cp)
-{
- while (*cp && !isspace(*cp))
- cp++;
-
- return cp;
-}
-
static int count_argc(const char *str)
{
int count = 0;
+ bool was_space;
- while (*str) {
- str = skip_spaces(str);
- if (*str) {
+ for (was_space = true; *str; str++) {
+ if (isspace(*str)) {
+ was_space = true;
+ } else if (was_space) {
+ was_space = false;
count++;
- str = skip_arg(str);
}
}
@@ -39,10 +33,8 @@ static int count_argc(const char *str)
*/
void argv_free(char **argv)
{
- char **p;
- for (p = argv; *p; p++)
- kfree(*p);
-
+ argv--;
+ kfree(argv[0]);
kfree(argv);
}
EXPORT_SYMBOL(argv_free);
@@ -62,40 +54,37 @@ EXPORT_SYMBOL(argv_free);
*/
char **argv_split(gfp_t gfp, const char *str, int *argcp)
{
- int argc = count_argc(str);
- char **argv = kzalloc(sizeof(*argv) * (argc+1), gfp);
- char **argvp;
-
- if (argv == NULL)
- goto out;
-
- if (argcp)
- *argcp = argc;
-
- argvp = argv;
-
- while (*str) {
- str = skip_spaces(str);
-
- if (*str) {
- const char *p = str;
- char *t;
-
- str = skip_arg(str);
+ char *argv_str;
+ bool was_space;
+ char **argv, **argv_ret;
+ int argc;
+
+ argv_str = kstrndup(str, KMALLOC_MAX_SIZE, gfp);
+ if (!argv_str)
+ return NULL;
+
+ argc = count_argc(argv_str);
+ argv = kmalloc(sizeof(*argv) * (argc + 2), gfp);
+ if (!argv) {
+ kfree(argv_str);
+ return NULL;
+ }
- t = kstrndup(p, str-p, gfp);
- if (t == NULL)
- goto fail;
- *argvp++ = t;
+ *argv = argv_str;
+ argv_ret = ++argv;
+ for (was_space = true; *argv_str; argv_str++) {
+ if (isspace(*argv_str)) {
+ was_space = true;
+ *argv_str = 0;
+ } else if (was_space) {
+ was_space = false;
+ *argv++ = argv_str;
}
}
- *argvp = NULL;
-
- out:
- return argv;
+ *argv = NULL;
- fail:
- argv_free(argv);
- return NULL;
+ if (argcp)
+ *argcp = argc;
+ return argv_ret;
}
EXPORT_SYMBOL(argv_split);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
poweroff-change-orderly_poweroff-to-use-schedule_work.patch
thinkpad-acpi-kill-hotkey_thread_mutex.patch
kthread-introduce-to_live_kthread.patch
kthread-kill-task_get_live_kthread.patch
posix_cpu_timer-consolidate-expiry-time-type.patch
posix_cpu_timers-consolidate-timer-list-cleanups.patch
posix_cpu_timers-consolidate-expired-timers-check.patch
lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch
lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch
argv_split-teach-it-to-handle-mutable-strings.patch
argv_split-teach-it-to-handle-mutable-strings-fix.patch
epoll-use-rcu-to-protect-wakeup_source-in-epitem.patch
ptrace-add-ability-to-retrieve-signals-without-removing-from-a-queue-v4.patch
selftest-add-a-test-case-for-ptrace_peeksiginfo.patch
usermodehelper-export-_exec-and-_setup-functions.patch
usermodehelper-export-_exec-and-_setup-functions-fix.patch
kmod-split-call-to-call_usermodehelper_fns.patch
keys-split-call-to-call_usermodehelper_fns.patch
coredump-remove-trailling-whitespaces.patch
split-remaining-calls-to-call_usermodehelper_fns.patch
kmod-remove-call_usermodehelper_fns.patch
coredump-only-sigkill-should-interrupt-the-coredumping-task.patch
coredump-ensure-that-sigkill-always-kills-the-dumping-thread.patch
coredump-sanitize-the-setting-of-signal-group_exit_code.patch
coredump-introduce-dump_interrupted.patch
coredump-factor-out-the-setting-of-pf_dumpcore.patch
coredump-change-wait_for_dump_helpers-to-use-wait_event_interruptible.patch
set_task_comm-kill-the-pointless-memset-wmb.patch
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