Messages in this thread | | | Date | Sat, 8 Aug 2009 09:56:21 +0300 | Subject | Re: [PATCH] fat: Read buffer overflow | From | Pekka Enberg <> |
| |
Hi Hirofumi-san,
Roel Kluin <roel.kluin@gmail.com> writes: >> If len is less or equal to 0, this results in a read of s[-1]. >> >> Signed-off-by: Roel Kluin <roel.kluin@gmail.com> >> --- >> diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c >> index 6f27853..114ff6d 100644 >> --- a/fs/fat/namei_vfat.c >> +++ b/fs/fat/namei_vfat.c >> @@ -202,6 +202,9 @@ static inline int vfat_is_used_badchars(const wchar_t *s, int len) >> { >> int i; >> >> + if (len <= 0) >> + return -EINVAL; >> + >> for (i = 0; i < len; i++) >> if (vfat_bad_char(s[i])) >> return -EINVAL;
On Sat, Aug 8, 2009 at 2:06 AM, OGAWA Hirofumi<hirofumi@mail.parknet.co.jp> wrote: > Um..., what case is this possible? vfat_add_entry() checks (len == 0). > And if xlate_to_uni() couldn't convert name, it should return the error.
Yes, but we pass "ulen" to vfat_is_used_badchars(). The value of "ulen" is a returned in the "longlen" argument of xlate_to_uni() which in turn is calculated as follows for the UTF-8 case:
int name_len = strlen(name); *outlen = utf8s_to_utf16s(name, PATH_MAX, (wchar_t *) outname); *outlen -= (name_len - len); *longlen = *outlen;
Maybe "*outlen" can never be negative because of some invariants that I don't see but it's so non-obvious to me that I'd like to see the explicit check in vfat_is_used_badchars().
Pekka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |