selinux: Add __GFP_NOWARN to allocation at str_read()

syzbot is hitting warning at str_read() [1] because len parameter can
become larger than KMALLOC_MAX_SIZE. We don't need to emit warning for
this case.

[1] https://syzkaller.appspot.com/bug?id=7f2f5aad79ea8663c296a2eedb81978401a908f0

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+ac488b9811036cea7ea0@syzkaller.appspotmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index e9394e7..f4eadd3 100644 (file)
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -1101,7 +1101,7 @@ static int str_read(char **strp, gfp_t flags, void *fp, u32 len)
        if ((len == 0) || (len == (u32)-1))
                return -EINVAL;
 
-       str = kmalloc(len + 1, flags);
+       str = kmalloc(len + 1, flags | __GFP_NOWARN);
        if (!str)
                return -ENOMEM;