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 BE3053546C8; Wed, 20 May 2026 17:47:20 +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=1779299241; cv=none; b=U9I2/qGcvtHmuOZp2CSYBWhxbaAYPlL8lVk/0FT20imTpmSIaYzAUg4/npAbbRuh+x988ZuVBoUpUqBDoonINfG0k+MgSv+4OowQk/ulMvzh509Q7X6rAMRViyUBSI6XXTWDH9h23NTZeGS6DLBvWdY/ay0zrnXLGaDgwkBMieQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779299241; c=relaxed/simple; bh=ecZWy2ABmoB58WgdpwNrd+u1fRRJfSVM8aXFcx9HhM8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GsINYJYC9Epz3+XBgOvefTTm+qOfbCXXzFAh7YDPLLjxnrDYCAQNwh8BV+Ke9XC4N4BEa/vNecHG1kwP+v/uFKNPKpLJvlKv2I5y2yNxc/q9wO9mMuSKY4G+hNRp1zQ08/3M8AgxX3FqKVWSKAGrKam+AQdBYk4FBu0M3Z078jo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aBwcou0A; 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="aBwcou0A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3108D1F000E9; Wed, 20 May 2026 17:47:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779299240; bh=5DjJ1dgirjKyFIuKfvo9K5MfA9Bb/jWY1f9WQabrrtg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aBwcou0AIvheiMmMaB/qHbbvoin07v06WwSTuA5JKZDuISj/Lc2LEtfIkbqjtjR+Z IIhyzUyYLeWT9LU+MoPIEbARw+KY1SOt9r55xC5v9Winh1jGRNVboaXTOOwL7ifPLT 9luvQw7/Ylx/23Vdc5+TICxMft/v/s59uVDvxlNw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Christian Brauner (Amutable)" , Sasha Levin Subject: [PATCH 6.18 717/957] eventpoll: use hlist_is_singular_node() in __ep_remove() Date: Wed, 20 May 2026 18:20:00 +0200 Message-ID: <20260520162150.097560015@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162134.554764788@linuxfoundation.org> References: <20260520162134.554764788@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner [ Upstream commit 3d9fd0abc94d8cd430cc7cd7d37ce5e5aae2cd2b ] Replace the open-coded "epi is the only entry in file->f_ep" check with hlist_is_singular_node(). Same semantics, and the helper avoids the head-cacheline access in the common false case. Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-1-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) Stable-dep-of: a6dc643c6931 ("eventpoll: fix ep_remove struct eventpoll / struct file UAF") Signed-off-by: Sasha Levin --- fs/eventpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index a8e30414d996c..23602de08fed2 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -856,7 +856,7 @@ static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force) to_free = NULL; head = file->f_ep; - if (head->first == &epi->fllink && !epi->fllink.next) { + if (hlist_is_singular_node(&epi->fllink, head)) { /* See eventpoll_release() for details. */ WRITE_ONCE(file->f_ep, NULL); if (!is_file_epoll(file)) { -- 2.53.0