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vfs: fix put_compat_statfs64() does not handle errors 

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>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
hifive-unleashed-5.1
Li Wang 2016-11-15 17:19:01 +08:00 committed by Al Viro
parent 450630975d
commit 64d2ab32ef
1 changed files with 3 additions and 3 deletions
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6
fs/compat.c
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@ -253,9 +253,9 @@ COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *,
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 */