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 C5B752DC78C; Thu, 2 Jul 2026 16:48:14 +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=1783010895; cv=none; b=KYYMPDtxNw2t+14hUAmrdQmqu3U7PR0EPrGGl1k1JUGVRP0FPaTny2h7f6vs+BnAg+NwM3QvA5vB+v0m+UlzTe9HbBPVtztx0At9QEYiXHR5zuLQjXRyVrdO5zc0qQZkjxtNofJC2ydFbGUCLN53bQFaNAlfq2z57/lygGiFzyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783010895; c=relaxed/simple; bh=11r4sCvE5MEGd5ofseH/TpllEIouzzBVA3/1+nGvofM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=INwhDq3e9eeNJFR9fUtDuGMuU5cdA9QB2JDi2pb78LDWYvXCIxRABNOHFhTS5errqAg2MoxtUd+yp9+zMmuv0RLw+Y2N8tAVyU1GuVNeuGNU87mLqJIy3qAlQjpZq0zN3ljJpn8GiT+JgCfTCVGwgAg6aEDR0N2/X24v3w+xX0M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ViUAZxPg; 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="ViUAZxPg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 388881F000E9; Thu, 2 Jul 2026 16:48:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783010894; bh=3j5wXu7JIUZHoeXFxFs4oAn3BxTIxcgB/4zdTFf/1OM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ViUAZxPg8f2Y9l0h2WmIOucVSomWAexNqKX6t5/xWfyns5rVDihl794SqDfHbL7m2 w6BlZtICLwJfUJqMJjo5n/C0NOdc6P/goHpslxs7EOJJjQm5Vs1YYuggqQlyQnFCXx bM9ypJ2V/3HyB0b/mD00U+hFNQIUGoM0jZ7ceR1k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Linus Torvalds , "Christian Brauner (Amutable)" , Quentin Schulz , Sasha Levin Subject: [PATCH 6.6 077/175] eventpoll: split __ep_remove() Date: Thu, 2 Jul 2026 18:19:38 +0200 Message-ID: <20260702155117.410559822@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155115.766838875@linuxfoundation.org> References: <20260702155115.766838875@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner [ Upstream commit 0f7bdfd413000985de09fc39eb9efa1e091a3ce0 ] Split __ep_remove() to delineate file removal from epoll item removal. Suggested-by: Linus Torvalds Link: https://patch.msgid.link/20260423-work-epoll-uaf-v1-2-2470f9eec0f5@kernel.org Signed-off-by: Christian Brauner (Amutable) Stable-dep-of: a6dc643c6931 ("eventpoll: fix ep_remove struct eventpoll / struct file UAF") Signed-off-by: Quentin Schulz Signed-off-by: Sasha Levin --- fs/eventpoll.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 4f05d12a05031a..ae9cb82764482c 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -715,6 +715,9 @@ static void ep_free(struct eventpoll *ep) kfree_rcu(ep, rcu); } +static void __ep_remove_file(struct eventpoll *ep, struct epitem *epi, struct file *file); +static bool __ep_remove_epi(struct eventpoll *ep, struct epitem *epi); + /* * Removes a "struct epitem" from the eventpoll RB tree and deallocates * all the associated resources. Must be called with "mtx" held. @@ -726,8 +729,6 @@ static void ep_free(struct eventpoll *ep) static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force) { struct file *file = epi->ffd.file; - struct epitems_head *to_free; - struct hlist_head *head; lockdep_assert_irqs_enabled(); @@ -743,8 +744,21 @@ static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force) return false; } - to_free = NULL; - head = file->f_ep; + __ep_remove_file(ep, epi, file); + return __ep_remove_epi(ep, epi); +} + +/* + * Called with &file->f_lock held, + * returns with it released + */ +static void __ep_remove_file(struct eventpoll *ep, struct epitem *epi, struct file *file) +{ + struct epitems_head *to_free = NULL; + struct hlist_head *head = file->f_ep; + + lockdep_assert_held(&ep->mtx); + if (hlist_is_singular_node(&epi->fllink, head)) { /* See eventpoll_release() for details. */ WRITE_ONCE(file->f_ep, NULL); @@ -758,6 +772,11 @@ static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force) hlist_del_rcu(&epi->fllink); spin_unlock(&file->f_lock); free_ephead(to_free); +} + +static bool __ep_remove_epi(struct eventpoll *ep, struct epitem *epi) +{ + lockdep_assert_held(&ep->mtx); rb_erase_cached(&epi->rbn, &ep->rbr); -- 2.53.0