[PATCH 1/4] watch_queue: Make watch_sizeof() check record size
From: David Howells <dhowells@redhat.com>
Date: 2020-07-24 13:11:44
Also in:
linux-api, linux-fsdevel, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
Make watch_sizeof() give a build error if the size of the struct won't fit into the size field in the header. Reported-by: Miklos Szeredi <redacted> Signed-off-by: David Howells <dhowells@redhat.com> --- include/linux/watch_queue.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/watch_queue.h b/include/linux/watch_queue.h
index 5e08db2adc31..38e04c7a7951 100644
--- a/include/linux/watch_queue.h
+++ b/include/linux/watch_queue.h@@ -120,7 +120,12 @@ static inline void remove_watch_list(struct watch_list *wlist, u64 id) * watch_sizeof - Calculate the information part of the size of a watch record, * given the structure size. */ -#define watch_sizeof(STRUCT) (sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT) +#define watch_sizeof(STRUCT) \ + ({ \ + size_t max = WATCH_INFO_LENGTH >> WATCH_INFO_LENGTH__SHIFT; \ + BUILD_BUG_ON(sizeof(STRUCT) > max); \ + sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT; \ + }) #endif