RE: [linuxwifi] [PATCH] net: wireless: intel: iwlwifi: dvm: fix tid mask

["Grumbach, Emmanuel" <emmanuel.grumbach@intel.com>]

Hi,

> Subject: [linuxwifi] [PATCH] net: wireless: intel: iwlwifi: dvm: fix tid mask
> 
> Currently the tid mask covers the first 4 bits of iwlagn_tx_resp::ra_tid,
> which gives 16 possible values for tid.
> This is problematic because IWL_MAX_TID_COUNT is 8, so indexing
> iwl_priv::tid_data can go very wrong.

True, OTOH we need tid to be 8 sometimes. We *just* need to make sure
that we don't index tid_data with this. Hence I think the proper fix is:

diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/tx.c b/drivers/net/wireless/intel/iwlwifi/dvm/tx.c
index 06ac3f1..16a8646 100644
--- a/drivers/net/wireless/intel/iwlwifi/dvm/tx.c
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/tx.c
@@ -1190,11 +1190,11 @@ void iwlagn_rx_reply_tx(struct iwl_priv *priv, struct iwl_rx_cmd_buffer *rxb)
                                next_reclaimed;
                        IWL_DEBUG_TX_REPLY(priv, "Next reclaimed packet:%d\n",
                                                  next_reclaimed);
+                       iwlagn_check_ratid_empty(priv, sta_id, tid);
                }

                iwl_trans_reclaim(priv->trans, txq_id, ssn, &skbs);

-               iwlagn_check_ratid_empty(priv, sta_id, tid);
                freed = 0;

                /* process frames */


Clearly calling iwlagn_check_ratid_empty with tid = IWL_TID_NON_QOS is a bad idea.

> 
> With UBSAN I can it happening while establishing the first connection
> after module load.
> 
> [  272.143440] UBSAN: Undefined behaviour in
> drivers/net/wireless/intel/iwlwifi/dvm/tx.c:777:32
> [  272.143447] index 8 is out of range for type 'iwl_tid_data [8]'
> [  272.143457] CPU: 0 PID: 4605 Comm: irq/32-iwlwifi Not tainted 4.12.0-dirty
> #2
> [  272.143460] Hardware name: Hewlett-Packard HP EliteBook 2560p/162B,
> BIOS 68SSU Ver. F.02 07/26/2011
> [  272.143462] Call Trace:
> [  272.143472]  dump_stack+0x9c/0x10b
> [  272.143477]  ? _atomic_dec_and_lock+0x285/0x285
> [  272.143486]  ubsan_epilogue+0xd/0x4e
> [  272.143493]  __ubsan_handle_out_of_bounds+0xef/0x118
> [  272.143498]  ? __ubsan_handle_shift_out_of_bounds+0x221/0x221
> [  272.143519]  ? iwl_trans_pcie_reclaim+0x153/0xc90 [iwlwifi]
> [  272.143539]  iwlagn_check_ratid_empty+0x337/0x410 [iwldvm]
> [  272.143556]  ? iwl_hcmd_names_cmp+0x2f/0x60 [iwlwifi]
> [  272.143571]  iwlagn_rx_reply_tx+0x8a4/0x1820 [iwldvm]
> 
> Signed-off-by: Seraphime Kirkovski <kirkseraph@gmail.com>
> ---
>    I'm currently running this patch on my machines and I have wifi.
>    The patch presumes а cleanup patch, I sent yesterday:
>       https://www.spinics.net/lists/kernel/msg2526314.html
> 
>  drivers/net/wireless/intel/iwlwifi/dvm/commands.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
> b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
> index 37d2ba5ae852..e5994df9ea4c 100644
> --- a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
> +++ b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
> @@ -1448,7 +1448,7 @@ struct agg_tx_status {
>   */
>  /* refer to ra_tid */
>  #define IWLAGN_TX_RES_TID_POS	0
> -#define IWLAGN_TX_RES_TID_MSK	0x0f
> +#define IWLAGN_TX_RES_TID_MSK	0x07
>  #define IWLAGN_TX_RES_RA_POS	4
>  #define IWLAGN_TX_RES_RA_MSK	0xf0
> 
> --
> 2.11.0
> 
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