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mlxsw: Warn about invalid accesses to array fields

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A forgotten or buggy variable initialization can cause out-of-bounds access
to a register or other item array field. For an overflow, such access would
mangle adjacent parts of the register payload. For an underflow, due to all
variables being unsigned, the access would likely trample unrelated memory.
Since neither is correct, replace these accesses with accesses at the index
of 0, and warn about the issue.

Suggested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://patch.msgid.link/b988fb265c2f6c1206fe12d5bfdcfa188b7672d1.1720447210.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Petr Machata 2024-07-08 16:23:40 +02:00 committed by Jakub Kicinski
parent 746d684ea5
commit b45c76e5f4
1 changed files with 4 additions and 0 deletions
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4
drivers/net/ethernet/mellanox/mlxsw/item.h
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@ -218,6 +218,10 @@ __mlxsw_item_bit_array_offset(const struct mlxsw_item *item,
}
max_index = (item->size.bytes << 3) / item->element_size - 1;
if (WARN_ONCE(index > max_index,
"name=%s,index=%u,max_index=%u\n", item->name, index,
max_index))
index = 0;
be_index = max_index - index;
offset = be_index * item->element_size >> 3;
in_byte_index = index % (BITS_PER_BYTE / item->element_size);