linux-kernel - [PATCH 4/6] exec: split prepare_arg

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Message-Id: <20200618144627.114057-5-hch@lst.de>
Date:   Thu, 18 Jun 2020 16:46:25 +0200
From:   Christoph Hellwig <hch@....de>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Arnd Bergmann <arnd@...db.de>, Brian Gerst <brgerst@...il.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        sparclinux@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] exec: split prepare_arg_pages

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@....de>
---
 fs/exec.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index a5d91f8b1341d5..34781db6bf6889 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -435,20 +435,10 @@ 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.
@@ -1886,7 +1876,19 @@ 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