From 3b5eed3c71a2fb60aa4405ad92a2a6ad2677f220 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 3 May 2022 13:54:58 -0700 Subject: netfs: Eliminate Clang randstruct warning Clang's structure layout randomization feature gets upset when it sees struct inode (which is randomized) cast to struct netfs_i_context. This is due to seeing the inode pointer as being treated as an array of inodes, rather than "something else, following struct inode". Since netfs can't use container_of() (since it doesn't know what the true containing struct is), it uses this direct offset instead. Adjust the code to better reflect what is happening: an arbitrary pointer is being adjusted and cast to something else: use a "void *" for the math. The resulting binary output is the same, but Clang no longer sees an unexpected cross-structure cast: In file included from ../fs/nfs/inode.c:50: In file included from ../fs/nfs/fscache.h:15: In file included from ../include/linux/fscache.h:18: ../include/linux/netfs.h:298:9: error: casting from randomized structure pointer type 'struct inode *' to 'struct netfs_i_context *' return (struct netfs_i_context *)(inode + 1); ^ 1 error generated. Cc: David Howells Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220503205503.3054173-2-keescook@chromium.org Reviewed-by: Jeff Layton Link: https://lore.kernel.org/lkml/7562f8eccd7cc0e447becfe9912179088784e3b9.camel@kernel.org --- include/linux/netfs.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/netfs.h') diff --git a/include/linux/netfs.h b/include/linux/netfs.h index c7bf1eaf51d5..0c33b715cbfd 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -295,7 +295,7 @@ extern void netfs_stats_show(struct seq_file *); */ static inline struct netfs_i_context *netfs_i_context(struct inode *inode) { - return (struct netfs_i_context *)(inode + 1); + return (void *)inode + sizeof(*inode); } /** @@ -307,7 +307,7 @@ static inline struct netfs_i_context *netfs_i_context(struct inode *inode) */ static inline struct inode *netfs_inode(struct netfs_i_context *ctx) { - return ((struct inode *)ctx) - 1; + return (void *)ctx - sizeof(struct inode); } /** -- cgit v1.2.3