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Date:   Thu, 30 May 2019 16:51:06 +0800
From:   Gen Zhang <blackgod016574@gmail.com>
To:     Ondrej Mosnacek <omosnace@redhat.com>
Cc:     Paul Moore <paul@paul-moore.com>, tony.luck@intel.com,
        Stephen Smalley <sds@tycho.nsa.gov>,
        Eric Paris <eparis@parisplace.org>, selinux@vger.kernel.org,
        Linux kernel mailing list <linux-kernel@vger.kernel.org>,
        bpf@vger.kernel.org
Subject: [PATCH v2] hooks: fix a missing-check bug in
 selinux_sb_eat_lsm_opts()
Message-ID: <20190530085106.GA2711@zhanggen-UX430UQ>
References: <20190530035310.GA9127@zhanggen-UX430UQ>
 <CAFqZXNv-54DJhd8gyUhwDo6RvmjFGSHo=+s-BVsL87S+u0cQxQ@mail.gmail.com>
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In selinux_sb_eat_lsm_opts(), 'arg' is allocated by kmemdup_nul(). It
returns NULL when fails. So 'arg' should be checked.

Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
Fixes: 99dbbb593fe6 ("selinux: rewrite selinux_sb_eat_lsm_opts()")
---
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 3ec702c..5a9e959 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2635,6 +2635,8 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
 						*q++ = c;
 				}
 				arg = kmemdup_nul(arg, q - arg, GFP_KERNEL);
+				if (!arg)
+					return -ENOMEM;
 			}
 			rc = selinux_add_opt(token, arg, mnt_opts);
 			if (unlikely(rc)) {