sorry, ping for comments~
On 15 November 2016 at 17:19, Li Wang <liwang@xxxxxxxxxx> wrote:
> put_compat_statfs64() does NOT return -1 and setting errno to EOVERFLOW
> when some variables(like: f_bsize) overflowed in the returned struct.
>
> The reason is that the ubuf->f_blocks is __u64 type, it couldn't be
> 4bits as the judgement in put_comat_statfs64(). Here correct the
> __u32 variables(in struct compat_statfs64) for comparison.
>
> reproducer:
> step1. mount hugetlbfs with two different pagesize on ppc64 arch.
>
> $ hugeadm --pool-pages-max 16M:0
> $ hugeadm --create-mount
> $ mount | grep -i hugetlbfs
> none on /var/lib/hugetlbfs/pagesize-16MB type hugetlbfs (rw,relatime,seclabel,pagesize=16777216)
> none on /var/lib/hugetlbfs/pagesize-16GB type hugetlbfs (rw,relatime,seclabel,pagesize=17179869184)
>
> step2. compile & run this C program.
>
> $ cat statfs64_test.c
>
> #define _LARGEFILE64_SOURCE
> #include <stdio.h>
> #include <sys/syscall.h>
> #include <sys/statfs.h>
>
> int main()
> {
> struct statfs64 sb;
> int err;
>
> err = syscall(SYS_statfs64, "/var/lib/hugetlbfs/pagesize-16GB", sizeof(sb), &sb);
> if (err)
> return -1;
>
> printf("sizeof f_bsize = %d, f_bsize=%ld\n", sizeof(sb.f_bsize), sb.f_bsize);
>
> return 0;
> }
>
> $ gcc -m32 statfs64_test.c
> $ ./a.out
> sizeof f_bsize = 4, f_bsize=0
>
> Signed-off-by: Li Wang <liwang@xxxxxxxxxx>
> ---
> fs/compat.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/compat.c b/fs/compat.c
> index bd064a2..543b48c 100644
> --- a/fs/compat.c
> +++ b/fs/compat.c
> @@ -253,9 +253,9 @@ static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *
>
> static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
> {
> - if (sizeof ubuf->f_blocks == 4) {
> - if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
> - kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
> + if (sizeof(ubuf->f_bsize) == 4) {
> + if ((kbuf->f_type | kbuf->f_bsize | kbuf->f_namelen |
> + kbuf->f_frsize | kbuf->f_flags) & 0xffffffff00000000ULL)
> return -EOVERFLOW;
> /* f_files and f_ffree may be -1; it's okay
> * to stuff that into 32 bits */
> --
> 1.8.3.1
>
--
Regards,
Li Wang
Email: wangli.ahau@xxxxxxxxx
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