[PATCH] Revert "ath9k: fix ath_tx_process_buffer() potential null ptr dereference"

ath_tx_process_buffer() doesn't dereference or check sta and passes it
to ath_tx_complete_aggr() and ath_tx_complete_buf().

ath_tx_complete_aggr() checks the pointer before use. No problem here.

ath_tx_complete_buf() doesn't check or dereference sta and passes it on
to ath_tx_complete(). ath_tx_complete() doesn't check or dereference sta,
but assigns it to tx_info->status.status_driver_data[0]

ath_tx_complete_buf() is called from ath_tx_complete_aggr() passing
null ieee80211_sta pointer.

There is a potential for dereference later on, if and when the
tx_info->status.status_driver_data[0]is referenced. In addition, the
rcu read lock might be released before referencing the contents.

ath_tx_complete_buf() should be fixed to check sta perhaps? Worth
looking into.

Reverting this patch because it doesn't solve the problem and introduces
memory leak by skipping buffer completion if the pointer (sta) is NULL.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
 drivers/net/wireless/ath/ath9k/xmit.c | 28 ++++++++++++---------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 735858144e3a..1d36aae3f7b6 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c

@@ -711,24 +711,20 @@ static void ath_tx_process_buffer(struct ath_softc *sc, struct ath_txq *txq,
 		ath_tx_count_airtime(sc, sta, bf, ts, tid->tidno);
 		if (ts->ts_status & (ATH9K_TXERR_FILT | ATH9K_TXERR_XRETRY))
 			tid->clear_ps_filter = true;
+	}
 
-		if (!bf_isampdu(bf)) {
-			if (!flush) {
-				info = IEEE80211_SKB_CB(bf->bf_mpdu);
-				memcpy(info->control.rates, bf->rates,
-				       sizeof(info->control.rates));
-				ath_tx_rc_status(sc, bf, ts, 1,
-						 txok ? 0 : 1, txok);
-				ath_dynack_sample_tx_ts(sc->sc_ah,
-							bf->bf_mpdu, ts, sta);
-			}
-			ath_tx_complete_buf(sc, bf, txq, bf_head, sta,
-					    ts, txok);
-		} else {
-			ath_tx_complete_aggr(sc, txq, bf, bf_head, sta,
-					     tid, ts, txok);
+	if (!bf_isampdu(bf)) {
+		if (!flush) {
+			info = IEEE80211_SKB_CB(bf->bf_mpdu);
+			memcpy(info->control.rates, bf->rates,
+			       sizeof(info->control.rates));
+			ath_tx_rc_status(sc, bf, ts, 1, txok ? 0 : 1, txok);
+			ath_dynack_sample_tx_ts(sc->sc_ah, bf->bf_mpdu, ts,
+						sta);
 		}
-	}
+		ath_tx_complete_buf(sc, bf, txq, bf_head, sta, ts, txok);
+	} else
+		ath_tx_complete_aggr(sc, txq, bf, bf_head, sta, tid, ts, txok);
 
 	if (!flush)
 		ath_txq_schedule(sc, txq);

-- 
2.27.0

Shuah Khan [off-list ref] wrote:

This reverts commit a56c14bb21b296fb6d395164ab62ef2e419e5069.

ath_tx_process_buffer() doesn't dereference or check sta and passes it
to ath_tx_complete_aggr() and ath_tx_complete_buf().

ath_tx_complete_aggr() checks the pointer before use. No problem here.

ath_tx_complete_buf() doesn't check or dereference sta and passes it on
to ath_tx_complete(). ath_tx_complete() doesn't check or dereference sta,
but assigns it to tx_info->status.status_driver_data[0]

ath_tx_complete_buf() is called from ath_tx_complete_aggr() passing
null ieee80211_sta pointer.

There is a potential for dereference later on, if and when the
tx_info->status.status_driver_data[0]is referenced. In addition, the
rcu read lock might be released before referencing the contents.

ath_tx_complete_buf() should be fixed to check sta perhaps? Worth
looking into.

Reverting this patch because it doesn't solve the problem and introduces
memory leak by skipping buffer completion if the pointer (sta) is NULL.

Fixes: a56c14bb21b2 ("ath9k: fix ath_tx_process_buffer() potential null ptr dereference")
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Kalle Valo <redacted>

Thanks. I added the commit id and Fixes tag to the commit log, see the new version above.

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210217211801.22540-1-skhan@linuxfoundation.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Shuah Khan [off-list ref] wrote:

This reverts commit a56c14bb21b296fb6d395164ab62ef2e419e5069.

ath_tx_process_buffer() doesn't dereference or check sta and passes it
to ath_tx_complete_aggr() and ath_tx_complete_buf().

ath_tx_complete_aggr() checks the pointer before use. No problem here.

ath_tx_complete_buf() doesn't check or dereference sta and passes it on
to ath_tx_complete(). ath_tx_complete() doesn't check or dereference sta,
but assigns it to tx_info->status.status_driver_data[0]

ath_tx_complete_buf() is called from ath_tx_complete_aggr() passing
null ieee80211_sta pointer.

There is a potential for dereference later on, if and when the
tx_info->status.status_driver_data[0]is referenced. In addition, the
rcu read lock might be released before referencing the contents.

ath_tx_complete_buf() should be fixed to check sta perhaps? Worth
looking into.

Reverting this patch because it doesn't solve the problem and introduces
memory leak by skipping buffer completion if the pointer (sta) is NULL.

Fixes: a56c14bb21b2 ("ath9k: fix ath_tx_process_buffer() potential null ptr dereference")
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Kalle Valo <redacted>

Patch applied to ath-next branch of ath.git, thanks.

14ebaeeff8d0 Revert "ath9k: fix ath_tx_process_buffer() potential null ptr dereference"

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210217211801.22540-1-skhan@linuxfoundation.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches