integrity: check the return value of audit_log_start()

audit_log_start() returns audit_buffer pointer on success or NULL on
error, so it is better to check the return value of it.

Fixes: 3323eec921ef ("integrity: IMA as an integrity service provider")
Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

diff --git a/security/integrity/integrity_audit.c b/security/integrity/integrity_audit.c
index 29220056207f4e51e83afda6965816d7032d5f6e..0ec5e4c22cb2a1066c2b897776ead6d3db72635c 100644 (file)
--- a/security/integrity/integrity_audit.c
+++ b/security/integrity/integrity_audit.c
@@ -45,6 +45,8 @@ void integrity_audit_message(int audit_msgno, struct inode *inode,
                return;
 
        ab = audit_log_start(audit_context(), GFP_KERNEL, audit_msgno);
+       if (!ab)
+               return;
        audit_log_format(ab, "pid=%d uid=%u auid=%u ses=%u",
                         task_pid_nr(current),
                         from_kuid(&init_user_ns, current_uid()),