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exec: introduce get_user_arg_ptr() helper

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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>
This commit is contained in:
Oleg Nesterov 2011-03-06 18:02:21 +01:00
parent bb3c90f0de
commit 1d1dbf8135
1 changed files with 25 additions and 11 deletions
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36
fs/exec.c
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@ -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;