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_arg(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 <o...@redhat.com>
---
lib/argv_split.c | 82 +++++++++++++++++++++++-------------------------------
1 files changed, 35 insertions(+), 47 deletions(-)
diff --git a/lib/argv_split.c b/lib/argv_split.c
index 1e9a6cb..dfa534d 100644
--- a/lib/argv_split.c
+++ b/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 +33,7 @@ static int count_argc(const char *str)
*/
void argv_free(char **argv)
{
- char **p;
- for (p = argv; *p; p++)
- kfree(*p);
-
+ kfree(argv[-1]);
kfree(argv);
}
EXPORT_SYMBOL(argv_free);
@@ -62,40 +53,37 @@ 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);
--
1.5.5.1
--
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