Messages in this thread Patch in this message | | | Date | Tue, 30 Nov 2010 21:00:45 +0100 | From | Oleg Nesterov <> | Subject | [PATCH 1/4] exec: introduce get_arg_ptr() helper |
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Introduce get_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> ---
fs/exec.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-)
--- K/fs/exec.c~1_get_arg_ptr 2010-11-30 18:30:45.000000000 +0100 +++ K/fs/exec.c 2010-11-30 19:14:54.000000000 +0100 @@ -390,6 +390,17 @@ err: return err; } +static const char __user * +get_arg_ptr(const char __user * const __user *argv, int argc) +{ + const char __user *ptr; + + if (get_user(ptr, argv + argc)) + return ERR_PTR(-EFAULT); + + return ptr; +} + /* * count() counts the number of strings in array ARGV. */ @@ -399,13 +410,14 @@ static int count(const char __user * con if (argv != NULL) { for (;;) { - const char __user * p; + const char __user *p = get_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; @@ -435,16 +447,18 @@ static int copy_strings(int argc, const int len; unsigned long pos; - if (get_user(str, argv+argc) || - !(len = strnlen_user(str, MAX_ARG_STRLEN))) { - ret = -EFAULT; + ret = -EFAULT; + str = get_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;
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