2023-09-15 19:10:40

by Gustavo A. R. Silva

Subject: [PATCH][next] mlxsw: Use size_mul() in call to struct_size()

If, for any reason, the open-coded arithmetic causes a wraparound, the
protection that `struct_size()` adds against potential integer overflows
is defeated. Fix this by hardening call to `struct_size()` with `size_mul()`.

Fixes: 2285ec872d9d ("mlxsw: spectrum_acl_bloom_filter: use struct_size() in kzalloc()")
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
index e2aced7ab454..95f63fcf4ba1 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
@@ -496,7 +496,7 @@ mlxsw_sp_acl_bf_init(struct mlxsw_sp *mlxsw_sp, unsigned int num_erp_banks)
* is 2^ACL_MAX_BF_LOG
*/
bf_bank_size = 1 << MLXSW_CORE_RES_GET(mlxsw_sp->core, ACL_MAX_BF_LOG);
- bf = kzalloc(struct_size(bf, refcnt, bf_bank_size * num_erp_banks),
+ bf = kzalloc(struct_size(bf, refcnt, size_mul(bf_bank_size, num_erp_banks)),
GFP_KERNEL);
if (!bf)
return ERR_PTR(-ENOMEM);
--
2.34.1

2023-09-16 07:45:52

by Kees Cook

Subject: Re: [PATCH][next] mlxsw: Use size_mul() in call to struct_size()

On Fri, Sep 15, 2023 at 01:01:23PM -0600, Gustavo A. R. Silva wrote:
> If, for any reason, the open-coded arithmetic causes a wraparound, the
> protection that `struct_size()` adds against potential integer overflows
> is defeated. Fix this by hardening call to `struct_size()` with `size_mul()`.
>
> Fixes: 2285ec872d9d ("mlxsw: spectrum_acl_bloom_filter: use struct_size() in kzalloc()")
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook

2023-09-18 16:10:16

by Ido Schimmel

Subject: Re: [PATCH][next] mlxsw: Use size_mul() in call to struct_size()

On Fri, Sep 15, 2023 at 01:01:23PM -0600, Gustavo A. R. Silva wrote:
> If, for any reason, the open-coded arithmetic causes a wraparound, the
> protection that `struct_size()` adds against potential integer overflows
> is defeated. Fix this by hardening call to `struct_size()` with `size_mul()`.
>
> Fixes: 2285ec872d9d ("mlxsw: spectrum_acl_bloom_filter: use struct_size() in kzalloc()")
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Reviewed-by: Ido Schimmel <[email protected]>