From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3DB8E3BFE5A; Tue, 16 Jun 2026 18:25:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781634349; cv=none; b=rnhHfGxv0v2DrJ2+NufpE/WjyA+zu/MhPaiKF/U4J662zPZpZRgoCeeXgU7NjmjKeLj9alAAZ4QtAF5ZXIbja8FpNfXcpEfc1vVdYQjJ0eYUDzIJdBFns8ghwDtHOLYffo0p6vHa4yhCCaSgHqmEbl2KZxcF2/ZHgofoH85q6ak= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781634349; c=relaxed/simple; bh=6E9iCTEtH/9E2Gxyg2vNUm8QCZBU5rU9AHqCtONeknU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aBWSUZKnesUn03jr2ZdKoIsHQVxTxZj6QMQ+BMv0EFCM67neyjj1iOlr9FxzJFaVOncIq3rzSA6UTNew0klAIStoDzapSbQ1O3v0GLRu33oeZ0/cOZKCNXGGUAnDHKp4REYLqyALOj4DJo82SZrp9mVT8eWMWh0uu5ELhop76U4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=15Mmnhv2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="15Mmnhv2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E15F1F000E9; Tue, 16 Jun 2026 18:25:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781634348; bh=fhS7qOStPcb1WRPk58Hvny8de9AdAkN4dCtTKBvqoHs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=15Mmnhv2jRM7pKaHmictf6rfAkeIdEIrX/i1HGg5kKGPVque+Xos3EtiqU3A0f8jR DpxjTzhALWED85DHUuGYlahLcRD3YEpct61fzLxLpjOPvp8yQA4vHDChwegdz1xu0O jCug1X9ba/Sw9AnrTKA6lBttUcEhf8t5kTbsTBBo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yifan Wu , Juefei Pu , Yuan Tan , Xin Liu , Zhengchuan Liang , Longxuan Yu , Ren Wei , Pavel Begunkov , Jens Axboe Subject: [PATCH 5.15 248/411] io_uring/poll: fix signed comparison in io_poll_get_ownership() Date: Tue, 16 Jun 2026 20:28:06 +0530 Message-ID: <20260616145114.133411006@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145100.376842714@linuxfoundation.org> References: <20260616145100.376842714@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Longxuan Yu Commit 326941b22806cbf2df1fbfe902b7908b368cce42 usptream. io_poll_get_ownership() uses a signed comparison to check whether poll_refs has reached the threshold for the slowpath: if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomic_read() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath. Fixes: a26a35e9019f ("io_uring: make poll refs more robust") Cc: stable@vger.kernel.org Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Zhengchuan Liang Signed-off-by: Longxuan Yu Signed-off-by: Ren Wei Reviewed-by: Pavel Begunkov Link: https://patch.msgid.link/3a3508b08bcd7f1bc3beff848ae6e1d73d355043.1775965597.git.ylong030@ucr.edu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -5525,7 +5525,7 @@ static bool io_poll_get_ownership_slowpa */ static inline bool io_poll_get_ownership(struct io_kiocb *req) { - if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) + if (unlikely((unsigned int)atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) return io_poll_get_ownership_slowpath(req); return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK); }