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 22C46395AE2; Sat, 30 May 2026 16:52:33 +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=1780159955; cv=none; b=BokGVWLVcsZrAyPafBhf6Ui2U4ebFMi42PVpCOB69Dli8mZ8Dwnr7noJKV+d+vfArb0nqoEEa5d8OSSbHiZMFGdOY+/tS4Vb+XrbwDaSJGKC0jHTafzZeOLfFQ5blAIv0cINaNNlR6Nesfoi7M0oghbqv2dO3HARJ6KlwwBwQWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780159955; c=relaxed/simple; bh=YtGnqfCs9aJXvYFVFzr5blna7/gM+CTr7DczFf3VKEA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JFHf0nsyRAlKl4XOrRF95l/NCLQk4g2zVpk1JGan1YJEbYvafkYBFJj7LwvXoZ0CQzHDR8GwlvCmeSYGqixFES5gxB9h+yBA6DqvM9Ncc4yDy6aC6jfg6ve/nJCDJEXHIb6P/RvpRcCXDRwEqvru+gHqGNPslsI3WDvLe+YYr30= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SAxw++Vz; 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="SAxw++Vz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE4A91F00899; Sat, 30 May 2026 16:52:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780159953; bh=2XmM8NLOc5/UYy5/87B6Qi9daJ8Ft0xl5zhrffonvfY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SAxw++Vza55bwrMN7FoUUpK3FtRHzRbAy3TqwjTvoRfgEtJ/dnC12Ztz2GxvMDtSH HcvKXjBcX82zpmz+YjI2Y9rI6+rpulvTZ6aTp3BFo9ose38clM3CDUwUPL7SE6y8zf QBjJvdXfvml74WiQ8F9r0+U9z1y8eetwVSOUwvS0= 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 6.1 206/969] io_uring/poll: fix signed comparison in io_poll_get_ownership() Date: Sat, 30 May 2026 17:55:30 +0200 Message-ID: <20260530160306.162794621@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160300.485627683@linuxfoundation.org> References: <20260530160300.485627683@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Longxuan Yu commit 326941b22806cbf2df1fbfe902b7908b368cce42 upstream. 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/poll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -88,7 +88,7 @@ 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); }