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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 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6D03920019 X-Stat-Signature: hqqb6tpwk46yma6csr1boahop9awntjz X-Rspam-User: X-HE-Tag: 1773334898-986376 X-HE-Meta: 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 mg6VCVQ5 S++Y0MGd2WsBqwGo7JcBhVaYaNWdxW0pu0ORpBHyTY6gm4DkSRfTgHyn528mS+h/+fCyxFLRFLuI/bxm8JpLvv+oq7sFVK/7odIpvyFGv90E73xXubqhxICFKq8kU7i8BeOy+qGUoJciGte43uPoIWStLgeBF/SFRMDOraQGknVYZcR6v9l8ITTVF2/Z8Wwv/IAehOEGnafGxlLXIhwKliT6NgU8pQPCHdH0hIC4lWNcXekvpDy782CU456TqpmOZGpLUx1YtaKL0topigr1/4vyMQ8YivlYD7UJPYiHY+jeUPyEu24436x4XG7Ys+Xh0U9BBNG32X4Gxpt2V5TUjp5EoFfbfgZpIca7ena7qqkxHbHoWcKY/VQHnbSW9fdixrKZ43rGRND318+lcYLzgqaUtJxfXmxcWzKHiOgUZQ1d1VYWRwLNOuw5ybWGndKLc1D3ZPzIWpHflnUQOdqul3pDmmRJcD0W59gVS Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 = *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