[PATCH v2] vfs: fix put_compat_statfs64() does not handle errors

[PATCH v2] vfs: fix put_compat_statfs64() does not handle errors

[Li Wang]

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@redhat.com>
---
 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

Re: [PATCH v2] vfs: fix put_compat_statfs64() does not handle errors

[Li Wang]

sorry, ping for comments~



On 15 November 2016 at 17:19, Li Wang <liwang@redhat.com> 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@redhat.com>
> ---
>  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@gmail.com

Re: [PATCH v2] vfs: fix put_compat_statfs64() does not handle errors

[Andreas Dilger]

[-- Attachment #1: Type: text/plain, Size: 2382 bytes --]


> On Nov 15, 2016, at 2:19 AM, Li Wang <liwang@redhat.com> 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@redhat.com>

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> 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
> 


Cheers, Andreas






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