From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3002C3C9896; Fri, 15 May 2026 16:05:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778861143; cv=none; b=KzfT7vohgw+RwCoekRNwGr1alIZbITfRt+pzV6KLEdytysHBqQg7f9uemM2ZWT+RNsLVF/9KP8TLuPznzJa1UJrsQC3CO0Trt01Ic/iK3fceCpUtk1z9XklL39FKLh+anKiCaNsYkyGIAwmyVwnNLxlFLaMujk95LCuLGHn5Jw4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778861143; c=relaxed/simple; bh=K4tcsQeZc2wf4qsA8BcViAOgapx9B+f1yALHQW20x0s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lOap9siFX/iyOnPJEmd6flTncw8+kQtyJijB0LSmcDhNm+meo4gJD9clSHq3P5gV19SvZoqURRnwKaHeCci+YrSp7EtJe2Bkdg8J942fzdLuhLDRfqlUvw/Kuuxs9xNJqI4xq9PQKTfzetTpmgE95VCtMmTS3LQKO3IKrSqNBYA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Q2ZDaktD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Q2ZDaktD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA392C2BCB3; Fri, 15 May 2026 16:05:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778861143; bh=K4tcsQeZc2wf4qsA8BcViAOgapx9B+f1yALHQW20x0s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q2ZDaktDJ1J3xKjHwAXwVJpZEohCwFIuMoY7MhVVrDE3BqWTpc8Ynw67WSU2y1HGV HSqNcDyF7CdoKz8pAL6yOxpYBm29jsehfcVIDIxua2fRYWcFp2NSMsG9zW/A1g5GBT usqen9LV8/3xgO04ZgzaRoR4bx6DgF4CkqlXykGg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Miklos Szeredi , Jan Kara Subject: [PATCH 6.6 216/474] fanotify: fix false positive on permission events Date: Fri, 15 May 2026 17:45:25 +0200 Message-ID: <20260515154719.684570347@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260515154715.053014143@linuxfoundation.org> References: <20260515154715.053014143@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: Miklos Szeredi commit 7746e3bd4cc19b5092e00d32d676e329bfcb6900 upstream. fsnotify_get_mark_safe() may return false for a mark on an unrelated group, which results in bypassing the permission check. Fix by skipping over detached marks that are not in the current group. CC: stable@vger.kernel.org Fixes: abc77577a669 ("fsnotify: Provide framework for dropping SRCU lock in ->handle_event") Signed-off-by: Miklos Szeredi Link: https://patch.msgid.link/20260410144950.156160-1-mszeredi@redhat.com Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- fs/notify/fsnotify.c | 2 +- fs/notify/mark.c | 18 +++++++++++------- include/linux/fsnotify_backend.h | 1 + 3 files changed, 13 insertions(+), 8 deletions(-) --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -398,7 +398,7 @@ static struct fsnotify_mark *fsnotify_fi return hlist_entry_safe(node, struct fsnotify_mark, obj_list); } -static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark) +struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark) { struct hlist_node *node = NULL; --- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -380,9 +380,6 @@ EXPORT_SYMBOL_GPL(fsnotify_put_mark); */ static bool fsnotify_get_mark_safe(struct fsnotify_mark *mark) { - if (!mark) - return true; - if (refcount_inc_not_zero(&mark->refcnt)) { spin_lock(&mark->lock); if (mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) { @@ -423,15 +420,22 @@ bool fsnotify_prepare_user_wait(struct f int type; fsnotify_foreach_iter_type(type) { + struct fsnotify_mark *mark = iter_info->marks[type]; + /* This can fail if mark is being removed */ - if (!fsnotify_get_mark_safe(iter_info->marks[type])) { - __release(&fsnotify_mark_srcu); - goto fail; + while (mark && !fsnotify_get_mark_safe(mark)) { + if (mark->group == iter_info->current_group) { + __release(&fsnotify_mark_srcu); + goto fail; + } + /* This is a mark in an unrelated group, skip */ + mark = fsnotify_next_mark(mark); + iter_info->marks[type] = mark; } } /* - * Now that both marks are pinned by refcount in the inode / vfsmount + * Now that all marks are pinned by refcount in the inode / vfsmount / etc * lists, we can drop SRCU lock, and safely resume the list iteration * once userspace returns. */ --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -817,6 +817,7 @@ static inline void fsnotify_clear_sb_mar } extern void fsnotify_get_mark(struct fsnotify_mark *mark); extern void fsnotify_put_mark(struct fsnotify_mark *mark); +struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark); extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info); extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);