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Subject: RE: [PATCH v3 2/3] RDMA/mana_ib: Prefer struct_size over open coded
 arithmetic
Thread-Topic: [PATCH v3 2/3] RDMA/mana_ib: Prefer struct_size over open coded
 arithmetic
Thread-Index: AQHaiDlNdYVeA1K4dE2VOPjC0rWojLFeyR3g
Date: Mon, 8 Apr 2024 19:42:13 +0000
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> Subject: [PATCH v3 2/3] RDMA/mana_ib: Prefer struct_size over open coded
> arithmetic
>
> This is an effort to get rid of all multiplications from allocation funct=
ions in order to
> prevent integer overflows [1][2].
>
> As the "req" variable is a pointer to "struct mana_cfg_rx_steer_req_v2"
> and this structure ends in a flexible array:
>
> struct mana_cfg_rx_steer_req_v2 {
>       [...]
>         mana_handle_t indir_tab[] __counted_by(num_indir_entries); };
>
> the preferred way in the kernel is to use the struct_size() helper to do =
the
> arithmetic instead of the calculation "size + size * count" in the kzallo=
c() function.
>
> Moreover, use the "offsetof" helper to get the indirect table offset inst=
ead of the
> "sizeof" operator and avoid the open-coded arithmetic in pointers using t=
he new
> flex member. This new structure member also allow us to remove the
> "req_indir_tab" variable since it is no longer needed.
>
> This way, the code is more readable and safer.
>
> This code was detected with the help of Coccinelle, and audited and modif=
ied
> manually.
>
> Link:
> https://www.ker/
> nel.org%2Fdoc%2Fhtml%2Flatest%2Fprocess%2Fdeprecated.html%23open-
> coded-arithmetic-in-allocator-
> arguments&data=3D05%7C02%7Clongli%40microsoft.com%7Cfcf2a410393a429633
> ca08dc56506b01%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63848
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> zsyXsS1s9xw%2FwaSEl3h4s6AeiykFG4KiJLzXOc%3D&reserved=3D0 [1]
> Link:
> https://github.co/
> m%2FKSPP%2Flinux%2Fissues%2F160&data=3D05%7C02%7Clongli%40microsoft.co
> m%7Cfcf2a410393a429633ca08dc56506b01%7C72f988bf86f141af91ab2d7cd01
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> pA%3D&reserved=3D0 [2]
> Signed-off-by: Erick Archer <erick.archer@outlook.com>

Reviewed-by: Long Li <longli@microsoft.com>