From 77d4ccbcdcda4392c162e461240e74ac70294ea2 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 21 Feb 2019 15:49:38 +0800 Subject: [PATCH] fanotify: Make sure to check event_len when copying mainline inclusion from mainline-5.0-rc1 commit 5b03a472b4e39c4e107d29543fd968c8abc3c873 category: bugfix bugzilla: 10640 CVE: NA --------------------------- As a precaution, make sure we check event_len when copying to userspace. Based on old feedback: https://lkml.kernel.org/r/542D9FE5.3010009@gmx.de Signed-off-by: Kees Cook Signed-off-by: Jan Kara Signed-off-by: yangerkun Reviewed-by: zhangyi (F) Signed-off-by: Yang Yingliang --- fs/notify/fanotify/fanotify_user.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 69054886915b..80d0a9554455 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -206,7 +206,7 @@ static int process_access_response(struct fsnotify_group *group, static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fsnotify_event *event, - char __user *buf) + char __user *buf, size_t count) { struct fanotify_event_metadata fanotify_event_metadata; struct file *f; @@ -220,6 +220,12 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, fd = fanotify_event_metadata.fd; ret = -EFAULT; + /* + * Sanity check copy size in case get_one_event() and + * fill_event_metadata() event_len sizes ever get out of sync. + */ + if (WARN_ON_ONCE(fanotify_event_metadata.event_len > count)) + goto out_close_fd; if (copy_to_user(buf, &fanotify_event_metadata, fanotify_event_metadata.event_len)) goto out_close_fd; @@ -295,7 +301,7 @@ static ssize_t fanotify_read(struct file *file, char __user *buf, continue; } - ret = copy_event_to_user(group, kevent, buf); + ret = copy_event_to_user(group, kevent, buf, count); if (unlikely(ret == -EOPENSTALE)) { /* * We cannot report events with stale fd so drop it. -- GitLab