netdev - Re: [PATCH net] qede: avoid uninitialized entries in coal

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Date:   Mon, 27 Feb 2023 10:51:49 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Michal Schmidt <mschmidt@...hat.com>
Cc:     netdev@...r.kernel.org, Manish Chopra <manishc@...vell.com>,
        Ariel Elior <aelior@...vell.com>,
        Alok Prasad <palok@...vell.com>
Subject: Re: [PATCH net] qede: avoid uninitialized entries in coal_entry
 array

On Fri, 24 Feb 2023 01:41:45 +0100 Michal Schmidt wrote:
> Even after commit 908d4bb7c54c ("qede: fix interrupt coalescing
> configuration"), some entries of the coal_entry array may theoretically
> be used uninitialized:
> 
>  1. qede_alloc_fp_array() allocates QEDE_MAX_RSS_CNT entries for
>     coal_entry. The initial allocation uses kcalloc, so everything is
>     initialized.
>  2. The user sets a small number of queues (ethtool -L).
>     coal_entry is reallocated for the actual small number of queues.
>  3. The user sets a bigger number of queues.
>     coal_entry is reallocated bigger. The added entries are not
>     necessarily initialized.
> 
> In practice, the reallocations will actually keep using the originally
> allocated region of memory, but we should not rely on it.
> 
> The reallocation is unnecessary. coal_entry can always have
> QEDE_MAX_RSS_CNT entries.
> 
> Fixes: 908d4bb7c54c ("qede: fix interrupt coalescing configuration")
> Signed-off-by: Michal Schmidt <mschmidt@...hat.com>

Applied, thanks!