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Subject[PATCH] vfs: fix statfs64() returning impossible EOVERFLOW for 64-bit f_files
Date
compat_statfs64 structure has some 32-bit and some 64-bit fields, so
64d2ab32e "vfs: fix put_compat_statfs64() does not handle errors" fixed
32-bit overflow checks not being performed, but accidentally enabled
checks for f_files and f_ffree that are 64-bit and cannot have overflow.
Now checks for both groups of fields are enabled by different
conditions.

This broke my Steam runtime and can be reproduced with this test case:

# mount -t tmpfs -o nr_inodes=4294967297 tmpfs /mnt
$ cat statfs.c

int main() {
struct statvfs sv;
statvfs("/mnt", &sv);
printf("%d %llu %llu\n", errno,
(unsigned long long) sv.f_files,
(unsigned long long) sv.f_ffree);
return 0;
}
$ gcc -g -m32 -D_FILE_OFFSET_BITS=64 statfs.c
$ ./a.out
75 134513445 0
| \- some junk on stack
EOVERFLOW

Signed-off-by: Sergey Klyaus <sergey.m.klyaus@gmail.com>
---
fs/statfs.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/statfs.c b/fs/statfs.c
index fab9b6a3c116..073bb2d1871e 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -307,6 +307,8 @@ static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstat
if ((kbuf->f_type | kbuf->f_bsize | kbuf->f_namelen |
kbuf->f_frsize | kbuf->f_flags) & 0xffffffff00000000ULL)
return -EOVERFLOW;
+ }
+ if (sizeof(ubuf->f_blocks) == 4) {
/* f_files and f_ffree may be -1; it's okay
* to stuff that into 32 bits */
if (kbuf->f_files != 0xffffffffffffffffULL
--
2.14.1
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