From: Helge Deller <deller@xxxxxx>
Subject: fat: use pointer to simple type in put_user()
The put_user(val,ptr) macro wants a pointer to a simple type, but in
fat_ioctl_filldir() the d_name field references an "array of chars". Be
more accurate and explicitly give the pointer to the first character of
the d_name[] array.
I noticed that issue while trying to optimize the parisc put_user() macro
and used an intermediate variable to store the pointer. In that case I
got this error:
In file included from include/linux/uaccess.h:11,
from include/linux/compat.h:17,
from fs/fat/dir.c:18:
fs/fat/dir.c: In function `fat_ioctl_filldir':
fs/fat/dir.c:725:33: error: invalid initializer
725 | if (put_user(0, d2->d_name) || \
| ^~
include/asm/uaccess.h:152:33: note: in definition of macro `__put_user'
152 | __typeof__(ptr) __ptr = ptr; \
| ^~~
fs/fat/dir.c:759:1: note: in expansion of macro `FAT_IOCTL_FILLDIR_FUNC'
759 | FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
Andreas Schwab <schwab@xxxxxxxxxxxxxx> suggested to use
__typeof__(&*(ptr)) __ptr = ptr;
instead. This works, but nevertheless it's probably reasonable to
fix the original caller too.
Link: https://lkml.kernel.org/r/Ygo+A9MREmC1H3kr@p100
Signed-off-by: Helge Deller <deller@xxxxxx>
Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fat/dir.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/fat/dir.c~fat-use-pointer-to-simple-type-in-put_user
+++ a/fs/fat/dir.c
@@ -722,7 +722,7 @@ static int func(struct dir_context *ctx,
if (name_len >= sizeof(d1->d_name)) \
name_len = sizeof(d1->d_name) - 1; \
\
- if (put_user(0, d2->d_name) || \
+ if (put_user(0, &d2->d_name[0]) || \
put_user(0, &d2->d_reclen) || \
copy_to_user(d1->d_name, name, name_len) || \
put_user(0, d1->d_name + name_len) || \
_
