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 AE819369990; Sat, 12 Sep 2026 08:12:46 +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=1789200767; cv=none; b=BGtPOGKADIDBT1Rix4pkUe3JGnek+9Z5mPwm28rhwdMkWX7op7r9jm+y2eDs44gRBIYTknvz6KOkjZw6rYYzxpoZGOYdFiaH6TX+m+o9CJ3ur+SfL3D2OsKQPgSSHFPbBJyVLtDR41+mQ/czApUBGJeL7atop8xxmD85ehIgDGM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789200767; c=relaxed/simple; bh=Brui9M2wnTzoERJwv9vElqy9YwAl3jvx3vLOK4mRWAs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YVSQdO8XpLUh5mtnrdR4MC2PxwSOnrMc5JGuwjoniJzbjZnP/6ZyDIv7VhwbyKlZo5lLKGCLRLYuCaf0spMp8sPg5/7i7MM45bZhPkq8Cv9IJ9G9WWOGn4tAm1PKlTSceuZGJmswaFh+kHaITmtYQJkoTwqWAFcHOCsnGdqXJq0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2D0O3x+O; 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="2D0O3x+O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B31001F000FF; Sat, 12 Sep 2026 08:12:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789200766; bh=+1otnMORT7nx9jHQX/AHyygw8wT81UKlfCMn1oveGRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2D0O3x+O4atPliygUW+yCNEWgO7Ch35BFKZgwLolAk4QrZJ8b2xBp+zoyWeyPDzcn u7nfmVdrL4Z2Vyao2pn6CXJ7H9wyrpcAiVw/aqUK1RP+nCJWKNlnnto7AqaqG3UXdX DwBQAMrc859nDH7VdHcaClmNRjA+MT2ddGY2wjqg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yichong Chen , Jan Kara , Sasha Levin Subject: [PATCH 7.2 0857/1815] fanotify: report full event length for FIONREAD Date: Sat, 12 Sep 2026 08:43:27 +0200 Message-ID: <20260912065709.041223749@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065648.999753832@linuxfoundation.org> References: <20260912065648.999753832@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 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yichong Chen [ Upstream commit 68615158c12de36220446dfea5cfdf9ba6c19690 ] fanotify_ioctl(FIONREAD) reports the number of bytes available to read from the event queue. It currently accounts only FAN_EVENT_METADATA_LEN for each queued event. That underestimates events that carry additional information records, such as FAN_REPORT_DFID_NAME events. A userspace program that uses FIONREAD to size its read buffer can receive a length that is smaller than the next event. Reading with that buffer then fails with -EINVAL, while a larger buffer succeeds and reports a larger metadata.event_len. Use fanotify_event_len() when summing queued events so FIONREAD includes all info records. Fixes: 5e469c830fdb ("fanotify: copy event fid info to user") Signed-off-by: Yichong Chen Link: https://patch.msgid.link/20260731021827.602479-1-chenyichong@uniontech.com Signed-off-by: Jan Kara Signed-off-by: Sasha Levin --- fs/notify/fanotify/fanotify_user.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 9ec8fa6a27a67..a32c6634d5927 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1147,11 +1147,13 @@ static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long ar { struct fsnotify_group *group; struct fsnotify_event *fsn_event; + unsigned int info_mode; void __user *p; int ret = -ENOTTY; size_t send_len = 0; group = file->private_data; + info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); p = (void __user *) arg; @@ -1159,7 +1161,8 @@ static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long ar case FIONREAD: spin_lock(&group->notification_lock); list_for_each_entry(fsn_event, &group->notification_list, list) - send_len += FAN_EVENT_METADATA_LEN; + send_len += fanotify_event_len(info_mode, + FANOTIFY_E(fsn_event)); spin_unlock(&group->notification_lock); ret = put_user(send_len, (int __user *) p); break; -- 2.53.0