From e6cfaf34be9fcd1a8285a294e18986bfc41a409c Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 5 Dec 2022 11:33:40 -0800
Subject: [PATCH] proc: avoid integer type confusion in get_proc_long
Git-commit: e6cfaf34be9fcd1a8285a294e18986bfc41a409c
Patch-mainline: v6.1
References: CVE-2022-4378 bsc#1206207

proc_get_long() is passed a size_t, but then assigns it to an 'int'
variable for the length.  Let's not do that, even if our IO paths are
limited to MAX_RW_COUNT (exactly because of these kinds of type errors).

So do the proper test in the rigth type.

Reported-by: Kyle Zeng <zengyhkyle@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 kernel/sysctl.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 188c305aeb8b..8898ddeaaf75 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -342,13 +342,12 @@ static int proc_get_long(char **buf, size_t *size,
 			  unsigned long *val, bool *neg,
 			  const char *perm_tr, unsigned perm_tr_len, char *tr)
 {
-	int len;
 	char *p, tmp[TMPBUFLEN];
+	ssize_t len = *size;
 
-	if (!*size)
+	if (len <= 0)
 		return -EINVAL;
 
-	len = *size;
 	if (len > TMPBUFLEN - 1)
 		len = TMPBUFLEN - 1;
 
-- 
2.35.3