2018-01-31 05:53:28

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH] libceph: use 64-bit arithmetic instead of 32-bit

Cast objsetno to u64 in order to give the compiler complete
information about the proper arithmetic to use. Notice
that this variable is used in a context that expects an
expression of type u64 (64 bits, unsigned).

The expression objsetno * sc + stripepos is currently
being evaluated using 32-bit arithmetic.

In general, the use of incorrect arithmetic has security
implications.

Addresses-Coverity-ID: 200686
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
net/ceph/osdmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 0da27c6..58dc965 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -2183,7 +2183,7 @@ int ceph_calc_file_object_mapping(struct ceph_file_layout *layout,
stripepos = bl % sc;
objsetno = stripeno / su_per_object;

- *ono = objsetno * sc + stripepos;
+ *ono = (u64)objsetno * sc + stripepos;
dout("objset %u * sc %u = ono %u\n", objsetno, sc, (unsigned int)*ono);

/* *oxoff = *off % layout->fl_stripe_unit; # offset in su */
--
2.7.4



2018-01-31 09:47:18

by Ilya Dryomov

[permalink] [raw]
Subject: Re: [PATCH] libceph: use 64-bit arithmetic instead of 32-bit

On Wed, Jan 31, 2018 at 6:29 AM, Gustavo A. R. Silva
<[email protected]> wrote:
> Cast objsetno to u64 in order to give the compiler complete
> information about the proper arithmetic to use. Notice
> that this variable is used in a context that expects an
> expression of type u64 (64 bits, unsigned).
>
> The expression objsetno * sc + stripepos is currently
> being evaluated using 32-bit arithmetic.
>
> In general, the use of incorrect arithmetic has security
> implications.
>
> Addresses-Coverity-ID: 200686
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> net/ceph/osdmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
> index 0da27c6..58dc965 100644
> --- a/net/ceph/osdmap.c
> +++ b/net/ceph/osdmap.c
> @@ -2183,7 +2183,7 @@ int ceph_calc_file_object_mapping(struct ceph_file_layout *layout,
> stripepos = bl % sc;
> objsetno = stripeno / su_per_object;
>
> - *ono = objsetno * sc + stripepos;
> + *ono = (u64)objsetno * sc + stripepos;
> dout("objset %u * sc %u = ono %u\n", objsetno, sc, (unsigned int)*ono);
>
> /* *oxoff = *off % layout->fl_stripe_unit; # offset in su */

Hi Gustavo,

This (and other u32/u64 issues in this function, is this the only
warning?) is fixed in my striping v2 work branch. I wasn't going to
push that patch separately, but I guess I should post it.

Thanks,

Ilya

2018-01-31 12:25:42

by Gustavo A. R. Silva

[permalink] [raw]
Subject: Re: [PATCH] libceph: use 64-bit arithmetic instead of 32-bit

Hello Ilya,

Quoting Ilya Dryomov <[email protected]>:

> On Wed, Jan 31, 2018 at 6:29 AM, Gustavo A. R. Silva
> <[email protected]> wrote:
>> Cast objsetno to u64 in order to give the compiler complete
>> information about the proper arithmetic to use. Notice
>> that this variable is used in a context that expects an
>> expression of type u64 (64 bits, unsigned).
>>
>> The expression objsetno * sc + stripepos is currently
>> being evaluated using 32-bit arithmetic.
>>
>> In general, the use of incorrect arithmetic has security
>> implications.
>>
>> Addresses-Coverity-ID: 200686
>> Signed-off-by: Gustavo A. R. Silva <[email protected]>
>> ---
>> net/ceph/osdmap.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
>> index 0da27c6..58dc965 100644
>> --- a/net/ceph/osdmap.c
>> +++ b/net/ceph/osdmap.c
>> @@ -2183,7 +2183,7 @@ int ceph_calc_file_object_mapping(struct
>> ceph_file_layout *layout,
>> stripepos = bl % sc;
>> objsetno = stripeno / su_per_object;
>>
>> - *ono = objsetno * sc + stripepos;
>> + *ono = (u64)objsetno * sc + stripepos;
>> dout("objset %u * sc %u = ono %u\n", objsetno, sc,
>> (unsigned int)*ono);
>>
>> /* *oxoff = *off % layout->fl_stripe_unit; # offset in su */
>
> Hi Gustavo,
>
> This (and other u32/u64 issues in this function, is this the only
> warning?) is fixed in my striping v2 work branch. I wasn't going to
> push that patch separately, but I guess I should post it.
>

Yeah, this was the only one warning reported by Coverity in this
particular module.

Thanks
--
Gustavo