> get.size is unsigned int, UINT_MAX is 0x FFFFFFFF, not 0x7FFFFFFF > And you're metioning "addition", then why you're checking as "multiplication"? oh, my falut:( the patch is multiplication check, not addition check. thanks for helping me:) On Tue, Mar 23, 2010 at 11:05 AM, Xiaotian Feng <xtfeng@xxxxxxxxx> wrote: > On Tue, Mar 23, 2010 at 10:37 AM, wzt wzt <wzt.wzt@xxxxxxxxx> wrote: >>> Patrick's point is that you're using "if (get.size >= INT_MAX / >>> sizeof(struct ipt_get_entries))" >>> So, did you find any chance that get.size * sizeof(struct >>> ipt_get_entries) >= INT_MAX ? >>> >> would you carefully read my explain??? >> get.size is copy from the user space, it can be set as 0x7fffffff, >> addition with sizeof(struct ipt_get_entries) can be overflow. >> > > get.size is unsigned int, UINT_MAX is 0x FFFFFFFF, not 0x7FFFFFFF > And you're metioning "addition", then why you're checking as "multiplication"? > >>> And, for the addition overflow, can it be caught by >>> >>> "if (*len != sizeof(struct ipt_get_entries) + get.size)" ??? >>> >> sizeof(struct ipt_get_entries) + get.size can be overflow as *len, >> get.size is control by user space with copy_from_user(). > > >> >> On Tue, Mar 23, 2010 at 10:29 AM, Xiaotian Feng <xtfeng@xxxxxxxxx> wrote: >>> On Tue, Mar 23, 2010 at 9:34 AM, wzt wzt <wzt.wzt@xxxxxxxxx> wrote: >>>>> I can see that the size might cause an overflow in the addition with >>>>> sizeof(struct ipt_get_entries) >>>> That's the integer overflow i pointed. >>>> get.size is copy from the user space, it can be set as 0x7fffffff, >>>> addition with sizeof(struct ipt_get_entries) can be overflow. >>> >>> Patrick's point is that you're using "if (get.size >= INT_MAX / >>> sizeof(struct ipt_get_entries))" >>> So, did you find any chance that get.size * sizeof(struct >>> ipt_get_entries) >= INT_MAX ? >>> >>> And, for the addition overflow, can it be caught by >>> >>> "if (*len != sizeof(struct ipt_get_entries) + get.size)" ??? >>> >>>> >>>> if (*len != sizeof(struct ipt_get_entries) + get.size) { >>>> duprintf("get_entries: %u != %zu\n", >>>> *len, sizeof(get) + get.size); >>>> return -EINVAL; >>>> } >>>> >>>> so, check get.size max value before addition with sizeof(struct >>>> ipt_get_entries) to prevent the integer overflow. >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> Please read the FAQ at http://www.tux.org/lkml/ >>>> >>> >> > -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html