linux-kernel - [PATCH 5/5] selinux: drop unnecessary NULL check

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Message-Id: <20220217142133.72205-4-cgzones@googlemail.com>
Date:   Thu, 17 Feb 2022 15:21:28 +0100
From:   Christian Göttsche <cgzones@...glemail.com>
To:     selinux@...r.kernel.org
Cc:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Ondrej Mosnacek <omosnace@...hat.com>,
        Serge Hallyn <serge@...lyn.com>,
        Austin Kim <austin.kim@....com>,
        Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>,
        Casey Schaufler <casey@...aufler-ca.com>,
        Yang Li <yang.lee@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH 5/5] selinux: drop unnecessary NULL check

Commit e3489f8974e1 ("selinux: kill selinux_sb_get_mnt_opts()")
introduced a NULL check on the context after a successful call to
security_sid_to_context().  This is on the one hand redundant after
checking for success and on the other hand insufficient on an actual
NULL pointer, since the context is passed to seq_escape() leading to a
call of strlen() on it.

Reported by Clang analyzer:

    In file included from security/selinux/hooks.c:28:
    In file included from ./include/linux/tracehook.h:50:
    In file included from ./include/linux/memcontrol.h:13:
    In file included from ./include/linux/cgroup.h:18:
    ./include/linux/seq_file.h:136:25: warning: Null pointer passed as 1st argument to string length function [unix.cstring.NullArg]
            seq_escape_mem(m, src, strlen(src), flags, esc);
                                   ^~~~~~~~~~~

Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
---
 security/selinux/hooks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 1e69f88eb326..ac802b99d36c 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1020,7 +1020,7 @@ static int show_sid(struct seq_file *m, u32 sid)
 	rc = security_sid_to_context(&selinux_state, sid,
 					     &context, &len);
 	if (!rc) {
-		bool has_comma = context && strchr(context, ',');
+		bool has_comma = strchr(context, ',');
 
 		seq_putc(m, '=');
 		if (has_comma)
-- 
2.35.1