The patch titled
Subject: kernel.h: fix new warnings for container_of()
has been added to the -mm tree. Its filename is
kernelh-handle-pointers-to-arrays-better-in-container_of-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernelh-handle-pointers-to-arrays-better-in-container_of-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernelh-handle-pointers-to-arrays-better-in-container_of-fix.patch
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------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: kernel.h: fix new warnings for container_of()
I see new warnings with gcc-7.0.1 with the modified container_of():
fs/f2fs/dir.c: In function 'F2FS_I':
fs/f2fs/f2fs.h:1122:385: note: found mismatched ssa struct pointer types: 'struct f2fs_inode_info' and 'struct inode'
This seems to happen for all structures that have a zero offset
between the member and the container structure, i.e. idential
pointers.
Reverting to an intermediate pointer avoids the warning, and using
a void pointer instead of the target type should also avoid
regressing on the previous patch again.
Fixes: mmotm ("kernel.h: handle pointers to arrays better in container_of()")
Link: http://lkml.kernel.org/r/20170620200940.90557-1-arnd@xxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kernel.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN include/linux/kernel.h~kernelh-handle-pointers-to-arrays-better-in-container_of-fix include/linux/kernel.h
--- a/include/linux/kernel.h~kernelh-handle-pointers-to-arrays-better-in-container_of-fix
+++ a/include/linux/kernel.h
@@ -852,10 +852,11 @@ static inline void ftrace_dump(enum ftra
*
*/
#define container_of(ptr, type, member) ({ \
+ void *__mptr = (void *)(ptr); \
BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
!__same_type(*(ptr), void), \
"pointer type mismatch in container_of()"); \
- ((type *)((char *)(ptr) - offsetof(type, member))); })
+ ((type *)(__mptr - offsetof(type, member))); })
/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
mm-madvise-enable-softhard-offline-of-hugetlb-pages-at-pgd-level-fix.patch
mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration-fix.patch
kernelh-handle-pointers-to-arrays-better-in-container_of-fix.patch
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