From 1d1dbf8135ab2f3603cc72e39e0f68784f453c39 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 6 Mar 2011 18:02:21 +0100 Subject: [PATCH] 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 Reviewed-by: KOSAKI Motohiro Tested-by: KOSAKI Motohiro --- fs/exec.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 5e62d26a4fec..b12e24fe1c5e 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; -- 2.34.1