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 E33143002A9; Tue, 12 May 2026 17:56:01 +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=1778608562; cv=none; b=bLQ3N+J0QqRmJ/foamLlJaIFJApiMgBW832fsYwkvybB68vimaz/ITfO9y+QLxm2P+sqjtrmNcWPIuR9PkBKsca5OZH9VJeYVeC1znUPijz1IdDnE8yLJr2gOS20L27KPNpq+UWYRtPMfixojoW6GGHekVkKnMZmq/MkGdJzOV8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778608562; c=relaxed/simple; bh=oc3sTGvG+hGC4UlNY3XnU5XWnfLvcS1RmTheiDt6i08=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ETlR8HHfjDDdATj+8hwEJmIX3f5DBKdKZR1Fk8mbsssinBoGlCGYb5NORqbQok32xhrs9lkqLoMvNXAsjnUkaS91qz4uZKr8NX26N6V5yWQ6lWvIAd9nOtk6UYLwGT5jL+H2tw82KCD37dZpSoNcADBD4J4/B90RzVxy3U9tbPA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pE9N9cv6; 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="pE9N9cv6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46AACC2BCB0; Tue, 12 May 2026 17:56:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778608561; bh=oc3sTGvG+hGC4UlNY3XnU5XWnfLvcS1RmTheiDt6i08=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pE9N9cv6c77ZUs1U+CTFiYmmb9aoIDbtOPwjp6h9ReNmzb1Otkt02cAgMvfjivkxI 0LD1b+UVFIkty+p04zYOzzWP7Sa527VsUjRHIhg9y60Cv8JB0U1TFvhsW57VKUTeup SUVG8Cl2UOKypjPcvP3T4qOa42+RAfpex5+yAe2k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Miklos Szeredi , Jan Kara Subject: [PATCH 6.18 085/270] fanotify: fix false positive on permission events Date: Tue, 12 May 2026 19:38:06 +0200 Message-ID: <20260512173940.249668928@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173938.452574370@linuxfoundation.org> References: <20260512173938.452574370@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: 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 @@ -444,7 +444,7 @@ 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 @@ -453,9 +453,6 @@ 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) { @@ -496,15 +493,22 @@ 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 @@ -912,6 +912,7 @@ extern void fsnotify_clear_marks_by_grou unsigned int obj_type); 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);