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Date: Mon, 13 Sep 2021 10:31:25 +0200 From: Simon Horman <simon.horman@...igine.com> To: Len Baker <len.baker@....com> Cc: Jakub Kicinski <kuba@...nel.org>, "David S. Miller" <davem@...emloft.net>, Kees Cook <keescook@...omium.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>, oss-drivers@...igine.com, netdev@...r.kernel.org, linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] nfp: Prefer struct_size over open coded arithmetic On Sun, Sep 12, 2021 at 03:10:57PM +0200, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@....com> Reviewed-by: Simon Horman <simon.horman@...igine.com> > --- > drivers/net/ethernet/netronome/nfp/nfp_net_repr.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c > index 3b8e675087de..369f6ae700c7 100644 > --- a/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c > +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_repr.c > @@ -499,8 +499,7 @@ struct nfp_reprs *nfp_reprs_alloc(unsigned int num_reprs) > { > struct nfp_reprs *reprs; > > - reprs = kzalloc(sizeof(*reprs) + > - num_reprs * sizeof(struct net_device *), GFP_KERNEL); > + reprs = kzalloc(struct_size(reprs, reprs, num_reprs), GFP_KERNEL); > if (!reprs) > return NULL; > reprs->num_reprs = num_reprs; > -- > 2.25.1 >
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