Messages in this thread Patch in this message | | | Date | Sun, 13 Feb 2022 23:10:27 +0100 | From | Helge Deller <> | Subject | [PATCH] fat: Use pointer to d_name[0] in put_user() for compat case |
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The put_user(val,ptr) macro wants a pointer in the second parameter, but in fat_ioctl_filldir() the d_name field references a whole "array of chars". Usually the compiler automatically converts it and uses a pointer to that array, but it's more clean to explicitly give the real pointer to where someting is put, which is in this case 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)
The patch below cleans it up.
Signed-off-by: Helge Deller <deller@gmx.de>
diff --git a/fs/fat/dir.c b/fs/fat/dir.c index c4a274285858..249825017da7 100644 --- a/fs/fat/dir.c +++ b/fs/fat/dir.c @@ -722,7 +722,7 @@ static int func(struct dir_context *ctx, const char *name, int name_len, \ 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) || \
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