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authorOleg Nesterov <oleg@redhat.com>2011-03-06 18:02:21 +0100
committerOleg Nesterov <oleg@redhat.com>2011-04-09 15:53:45 +0200
commit1d1dbf8135ab2f3603cc72e39e0f68784f453c39 (patch)
treee30b04b64f92a55200aab62d414fb1378f7bfaab /fs/exec.c
parentbb3c90f0de7b34995b5e35cf5dc97a3d428b3761 (diff)
exec: introduce get_user_arg_ptr() helper
Introduce get_user_arg_ptr() helper, convert count() and copy_strings() to use it. No functional changes, preparation. This helper is trivial, it just reads the pointer from argv/envp user-space array. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c36
1 files changed, 25 insertions, 11 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 5e62d26a4fe..b12e24fe1c5 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -398,6 +398,17 @@ err:
return err;
}
+static const char __user *
+get_user_arg_ptr(const char __user * const __user *argv, int nr)
+{
+ const char __user *ptr;
+
+ if (get_user(ptr, argv + nr))
+ return ERR_PTR(-EFAULT);
+
+ return ptr;
+}
+
/*
* count() counts the number of strings in array ARGV.
*/
@@ -407,13 +418,14 @@ static int count(const char __user * const __user * argv, int max)
if (argv != NULL) {
for (;;) {
- const char __user * p;
+ const char __user *p = get_user_arg_ptr(argv, i);
- if (get_user(p, argv))
- return -EFAULT;
if (!p)
break;
- argv++;
+
+ if (IS_ERR(p))
+ return -EFAULT;
+
if (i++ >= max)
return -E2BIG;
@@ -443,16 +455,18 @@ static int copy_strings(int argc, const char __user *const __user *argv,
int len;
unsigned long pos;
- if (get_user(str, argv+argc) ||
- !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
- ret = -EFAULT;
+ ret = -EFAULT;
+ str = get_user_arg_ptr(argv, argc);
+ if (IS_ERR(str))
goto out;
- }
- if (!valid_arg_len(bprm, len)) {
- ret = -E2BIG;
+ len = strnlen_user(str, MAX_ARG_STRLEN);
+ if (!len)
+ goto out;
+
+ ret = -E2BIG;
+ if (!valid_arg_len(bprm, len))
goto out;
- }
/* We're going to work our way backwords. */
pos = bprm->p;