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authorKees Cook <keescook@chromium.org>2018-12-04 15:44:46 -0800
committerJan Kara <jack@suse.cz>2018-12-05 12:47:22 +0100
commit5b03a472b4e39c4e107d29543fd968c8abc3c873 (patch)
treee92640a16dc4c161eb8911d1f649c889341df8d4 /fs/notify
parentd6f7aa9820f21a879af8ceda17b2ebd1cf4beb25 (diff)
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fanotify: Make sure to check event_len when copying
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 <keescook@chromium.org> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/notify')
-rw-r--r--fs/notify/fanotify/fanotify_user.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index e03be5071362..d9484a0ac6b3 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.