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SubjectRe: [PATCH] generic compat_sys_ustat
Christoph Hellwig wrote:
> Due to a different size of ino_t ustat needs a compat handler, but
> currently only x86 and mips provide one. Add a generic compat_sys_ustat
> and switch all architectures over to it.
>
> Found by Eric Sandeen when running xfstests/017 on ppc64, which causes
> stack smashing warnings on RHEL/Fedora due to the too large amount of
> data writen by the syscall.

...

> Index: linux-2.6/fs/compat.c
> ===================================================================
> --- linux-2.6.orig/fs/compat.c 2008-11-20 20:09:52.000000000 +0100
> +++ linux-2.6/fs/compat.c 2008-11-20 20:16:05.000000000 +0100
> @@ -378,6 +378,24 @@ out:
> return error;
> }
>
> +asmlinkage long compat_sys_ustat(unsigned dev, struct compat_ustat __user *u32)

Oh, I had also suggested that the use of "u32" here was slightly
confusing, it at least made me do a double-take with the unsigned 32 bit
type... not a big deal, but just thought I'd mention it.

Thanks,
-Eric

> +{
> + struct ustat *u = compat_alloc_user_space(sizeof(*u));
> + int ret;
> +
> + ret = sys_ustat(dev, u);
> + if (ret < 0)
> + return ret;
> +
> + if (!access_ok(VERIFY_WRITE, u32, sizeof(*u32)) ||
> + __put_user((compat_daddr_t) u->f_tfree, &u32->f_tfree) ||
> + __put_user((compat_ino_t) u->f_tinode, &u32->f_tfree) ||
> + __copy_to_user(&u32->f_fname, u->f_fname, sizeof(u32->f_fname)) ||
> + __copy_to_user(&u32->f_fpack, u->f_fpack, sizeof(u32->f_fpack)))
> + return -EFAULT;
> + return 0;
> +}
> +


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