[PATCH v8 26/32] fanotify: WARN_ON against too large file handles
From: Gabriel Krisman Bertazi <hidden>
Date: 2021-10-19 00:04:01
Also in:
linux-api, linux-fsdevel
Subsystem:
fanotify, filesystems (vfs and infrastructure), fsnotify: filesystem notification infrastructure, the rest · Maintainers:
Jan Kara, Alexander Viro, Christian Brauner, Linus Torvalds
struct fanotify_error_event, at least, is preallocated and isn't able to to handle arbitrarily large file handles. Future-proof the code by complaining loudly if a handle larger than MAX_HANDLE_SZ is ever found. Signed-off-by: Gabriel Krisman Bertazi <redacted> --- fs/notify/fanotify/fanotify.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index cedcb1546804..45df610debbe 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c@@ -360,13 +360,23 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group, static int fanotify_encode_fh_len(struct inode *inode) { int dwords = 0; + int fh_len; if (!inode) return 0; exportfs_encode_inode_fh(inode, NULL, &dwords, NULL); + fh_len = dwords << 2; - return dwords << 2; + /* + * struct fanotify_error_event might be preallocated and is + * limited to MAX_HANDLE_SZ. This should never happen, but + * safeguard by forcing an invalid file handle. + */ + if (WARN_ON_ONCE(fh_len > MAX_HANDLE_SZ)) + return 0; + + return fh_len; } /*
--
2.33.0