mlxsw: Use size_mul() in call to struct_size()

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

Posted by Gustavo A. R. Silva 2 years, 4 months ago

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 <gustavoars@kernel.org>
---
 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

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

Posted by Ido Schimmel 2 years, 4 months ago

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 <gustavoars@kernel.org>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>

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

Posted by Kees Cook 2 years, 4 months ago

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 <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook