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To:     cai@lca.pw
Cc:     saeedm@mellanox.com, tariqt@mellanox.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] net/mlx5e: always initialize frag->last_in_page
From:   David Miller <davem@davemloft.net>
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From: Qian Cai <cai@lca.pw>
Date: Thu,  1 Aug 2019 09:52:54 -0400

> The commit 069d11465a80 ("net/mlx5e: RX, Enhance legacy Receive Queue
> memory scheme") introduced an undefined behaviour below due to
> "frag->last_in_page" is only initialized in mlx5e_init_frags_partition()
> when,
> 
> if (next_frag.offset + frag_info[f].frag_stride > PAGE_SIZE)
> 
> or after bailed out the loop,
> 
> for (i = 0; i < mlx5_wq_cyc_get_size(&rq->wqe.wq); i++)
> 
> As the result, there could be some "frag" have uninitialized
> value of "last_in_page".
> 
> Later, get_frag() obtains those "frag" and check "frag->last_in_page" in
> mlx5e_put_rx_frag() and triggers the error during boot. Fix it by always
> initializing "frag->last_in_page" to "false" in
> mlx5e_init_frags_partition().
...
> Fixes: 069d11465a80 ("net/mlx5e: RX, Enhance legacy Receive Queue memory scheme")
> Signed-off-by: Qian Cai <cai@lca.pw>

Applied and queued up for -stable.