From: Dominique Martinet <asmadeus@codewreck.org>
Date: Wed, 3 Nov 2021 17:34:05 +0900
Subject: fscache_cookie_enabled: check cookie is valid before accessing it
Git-commit: 0dc54bd4d6e03be1f0b678c4297170b79f1a44ab
Patch-mainline: v5.16-rc1
References: jsc#SES-1880

fscache_cookie_enabled() could be called on NULL cookies and cause a
null pointer dereference when accessing cookie flags: just make sure
the cookie is valid first

Suggested-by: David Howells <dhowells@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 include/linux/fscache.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index a4dab5998613..3b2282c157f7 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -167,7 +167,7 @@ struct fscache_cookie {
 
 static inline bool fscache_cookie_enabled(struct fscache_cookie *cookie)
 {
-	return test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+	return fscache_cookie_valid(cookie) && test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
 }
 
 /*