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| author | Kees Cook <keescook@chromium.org> | 2018-12-04 15:44:46 -0800 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2018-12-05 12:47:22 +0100 |
| commit | 5b03a472b4e39c4e107d29543fd968c8abc3c873 (patch) | |
| tree | e92640a16dc4c161eb8911d1f649c889341df8d4 /fs/notify/fanotify/fanotify_user.c | |
| parent | d6f7aa9820f21a879af8ceda17b2ebd1cf4beb25 (diff) | |
| download | lwn-5b03a472b4e39c4e107d29543fd968c8abc3c873.tar.gz lwn-5b03a472b4e39c4e107d29543fd968c8abc3c873.zip | |
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/fanotify/fanotify_user.c')
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 10 |
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. |