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[37.27.107.159]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-38a67e5ecedsm9710711fa.21.2026.03.12.10.01.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 10:01:34 -0700 (PDT) From: Josh Law X-Google-Original-From: Josh Law To: Matthew Wilcox , Andrew Morton Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Josh Law , Josh Law Subject: [PATCH] lib/idr: fix infinite loop in idr_get_next() Date: Thu, 12 Mar 2026 17:01:33 +0000 Message-Id: <20260312170133.6488-1-objecting@objecting.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Josh Law From: Josh Law In idr_get_next(), if the returned id from idr_get_next_ul() is greater than INT_MAX, the function issues a warning and returns NULL without updating the *nextid pointer. This causes a soft lockup for any caller iterating over an IDR (e.g. via idr_for_each_entry) because they will receive NULL, fail to advance their index, and repeatedly query the same state forever. Fix this by setting *nextid to INT_MAX when the bounds check fails, ensuring the caller's iteration will terminate. Signed-off-by: Josh Law --- lib/idr.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/idr.c b/lib/idr.c index f25bd2b9e9a4..07098eb4ddc3 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -268,8 +268,10 @@ void *idr_get_next(struct idr *idr, int *nextid) unsigned long id =3D *nextid; void *entry =3D idr_get_next_ul(idr, &id); =20 - if (WARN_ON_ONCE(id > INT_MAX)) + if (WARN_ON_ONCE(id > INT_MAX)) { + *nextid =3D INT_MAX; return NULL; + } *nextid =3D id; return entry; } --=20 2.34.1