linux-kernel - [Linux-kernel-mentees] [PATCH] idr: remove WARN_ON

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Date:   Mon, 14 Sep 2020 12:47:24 +0530
From:   Anmol Karn <anmol.karan123@...il.com>
To:     willy@...radead.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        anmol.karan123@...il.com,
        syzbot+f7204dcf3df4bb4ce42c@...kaller.appspotmail.com
Subject: [Linux-kernel-mentees] [PATCH] idr: remove WARN_ON_ONCE() when trying to check id

idr_get_next() gives WARN_ON_ONCE() when it gets (id > INT_MAX) true
and this happens when syzbot does fuzzing, and that warning is
expected, but WARN_ON_ONCE() is not required here and, cecking
the condition and returning NULL value would be suffice.

Reference: commit b9959c7a347 ("filldir[64]: remove WARN_ON_ONCE() for bad directory entries")
Reported-and-tested-by: syzbot+f7204dcf3df4bb4ce42c@...kaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=f7204dcf3df4bb4ce42c 
Signed-off-by: Anmol Karn <anmol.karan123@...il.com>
---
 lib/idr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/idr.c b/lib/idr.c
index 4d2eef0259d2..7c67560c1ecd 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -266,7 +266,7 @@ void *idr_get_next(struct idr *idr, int *nextid)
 	unsigned long id = *nextid;
 	void *entry = idr_get_next_ul(idr, &id);
 
-	if (WARN_ON_ONCE(id > INT_MAX))
+	if (id > INT_MAX)
 		return NULL;
 	*nextid = id;
 	return entry;
-- 
2.28.0