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[37.27.107.159]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-38a67d6185csm10401921fa.3.2026.03.12.10.12.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 10:12:39 -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 Subject: [PATCH v2] lib/idr: fix infinite loop in idr_get_next() Date: Thu, 12 Mar 2026 17:12:38 +0000 Message-Id: <20260312171238.7961-1-objecting@objecting.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 41kn31oyxxrcirzx1m95bm1prxj9um7y X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: D17181C000B X-HE-Tag: 1773335562-924415 X-HE-Meta: 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 QVNhXbyl IDABDP4XQEzIDkZfBhcOnBjABp3PR120bKv42M3oaPcJ83IsKxH+RO+8KsMwMiS/zY2DAdGUh3xMrdc6aOO9xszv4Dkm4IbrndjJBR5VjlfnzU/PndTgWBfO4az1kff4zcOu9j9afimNPnb5lLlLhSLymuSAEAUhnQYK2TvOEhpGKi3B0Mb+J1bzTtSEaIeyi5L68cO0ALGGXSiYxJrqTKFlbiEP67SAHfiIaSx4QhWc79ljws0Awj6knPddGTFfBYbo6qQRBVMLuyaBPgp1grdnreSsdafcLJA/QEhv0Hqf5K40DcWyzANREqUmzhmEFh0NEVCRJg1LcF0DT7YfcTJGFlxFWf8CFdz9I6ouD0LrwbLiLM8v290OJ1DNw6t6XA6XqqdpXw6c+tImYo4w+h+p05fjFMjhS2d8+kNLZ9p3wOwU0OUFVV+xFiXVcCamGKtAhT35/DRehKC0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 = *nextid; void *entry = idr_get_next_ul(idr, &id); - if (WARN_ON_ONCE(id > INT_MAX)) + if (WARN_ON_ONCE(id > INT_MAX)) { + *nextid = INT_MAX; return NULL; + } *nextid = id; return entry; } -- 2.34.1