[PATCH 4/6] exec: split prepare_arg_pages

Christoph Hellwig
2020-06-15T13:02:01Z

Move counting the arguments and enviroment variables out of
prepare_arg_pages and rename the rest of the function to check_arg_limit.
This prepares for a version of do_execvat that takes kernel pointers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/exec.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 6e4d9d1ffa35fa..696b1e8180d7d8 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -439,20 +439,10 @@ static int count_strings(const char __user *const __user *argv)
return i;
}

-static int prepare_arg_pages(struct linux_binprm *bprm,
- const char __user *const __user *argv,
- const char __user *const __user *envp)
+static int check_arg_limit(struct linux_binprm *bprm)
{
unsigned long limit, ptr_size;

- bprm->argc = count_strings(argv);
- if (bprm->argc < 0)
- return bprm->argc;
-
- bprm->envc = count_strings(envp);
- if (bprm->envc < 0)
- return bprm->envc;
-
/*
* Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
* (whichever is smaller) for the argv+env strings.
@@ -1890,7 +1880,19 @@ int do_execveat(int fd, struct filename *filename,
if (retval)
goto out_unmark;

- retval = prepare_arg_pages(bprm, argv, envp);
+ bprm->argc = count_strings(argv);
+ if (bprm->argc < 0) {
+ retval = bprm->argc;
+ goto out;
+ }
+
+ bprm->envc = count_strings(envp);
+ if (bprm->envc < 0) {
+ retval = bprm->envc;
+ goto out;
+ }
+
+ retval = check_arg_limit(bprm);
if (retval < 0)
goto out;

--
2.26.2