Re: [PATCH] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc

[Lorenz Bauer]

On Tue, 26 Jan 2021 at 08:26, Bui Quang Minh <minhquangbui99@xxxxxxxxx> wrote:
>
> In 32-bit architecture, the result of sizeof() is a 32-bit integer so
> the expression becomes the multiplication between 2 32-bit integer which
> can potentially leads to integer overflow. As a result,
> bpf_map_area_alloc() allocates less memory than needed.
>
> Fix this by casting 1 operand to u64.

Some quick thoughts:
* Should this have a Fixes tag?
* Seems like there are quite a few similar calls scattered around
(cpumap, etc.). Did you audit these as well?
* I'd prefer a calloc style version of bpf_map_area_alloc although
that might conflict with Fixes tag.

Lorenz

-- 
Lorenz Bauer  |  Systems Engineer
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