Re: [PATCH v2] net/mlx5e: always initialize frag->last_in_page

[David Miller]

From: Qian Cai <cai@xxxxxx>
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@xxxxxx>

Applied and queued up for -stable.