diff mbox series

[v5] wifi: mac80211: fix initialization of rx->link and rx->link_sta

Message ID 20221230200747.19040-1-nbd@nbd.name
State New
Headers show
Series [v5] wifi: mac80211: fix initialization of rx->link and rx->link_sta | expand

Commit Message

Felix Fietkau Dec. 30, 2022, 8:07 p.m. UTC 
There are some codepaths that do not initialize rx->link_sta properly. This
causes a crash in places which assume that rx->link_sta is valid if rx->sta
is valid.
One known instance is triggered by __ieee80211_rx_h_amsdu being called from
fast-rx. It results in a crash like this one:

 BUG: kernel NULL pointer dereference, address: 00000000000000a8
 #PF: supervisor write access in kernel mode
 #PF: error_code(0x0002) - not-present page PGD 0 P4D 0
 Oops: 0002 [#1] PREEMPT SMP PTI
 CPU: 1 PID: 506 Comm: mt76-usb-rx phy Tainted: G            E      6.1.0-debian64x+1.7 #3
 Hardware name: ZOTAC ZBOX-ID92/ZBOX-IQ01/ZBOX-ID92/ZBOX-IQ01, BIOS B220P007 05/21/2014
 RIP: 0010:ieee80211_deliver_skb+0x62/0x1f0 [mac80211]
 Code: 00 48 89 04 24 e8 9e a7 c3 df 89 c0 48 03 1c c5 a0 ea 39 a1 4c 01 6b 08 48 ff 03 48
       83 7d 28 00 74 11 48 8b 45 30 48 63 55 44 <48> 83 84 d0 a8 00 00 00 01 41 8b 86 c0
       11 00 00 8d 50 fd 83 fa 01
 RSP: 0018:ffff999040803b10 EFLAGS: 00010286
 RAX: 0000000000000000 RBX: ffffb9903f496480 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: ffff999040803ce0 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8d21828ac900
 R13: 000000000000004a R14: ffff8d2198ed89c0 R15: ffff8d2198ed8000
 FS:  0000000000000000(0000) GS:ffff8d24afe80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00000000000000a8 CR3: 0000000429810002 CR4: 00000000001706e0
 Call Trace:
  <TASK>
  __ieee80211_rx_h_amsdu+0x1b5/0x240 [mac80211]
  ? ieee80211_prepare_and_rx_handle+0xcdd/0x1320 [mac80211]
  ? __local_bh_enable_ip+0x3b/0xa0
  ieee80211_prepare_and_rx_handle+0xcdd/0x1320 [mac80211]
  ? prepare_transfer+0x109/0x1a0 [xhci_hcd]
  ieee80211_rx_list+0xa80/0xda0 [mac80211]
  mt76_rx_complete+0x207/0x2e0 [mt76]
  mt76_rx_poll_complete+0x357/0x5a0 [mt76]
  mt76u_rx_worker+0x4f5/0x600 [mt76_usb]
  ? mt76_get_min_avg_rssi+0x140/0x140 [mt76]
  __mt76_worker_fn+0x50/0x80 [mt76]
  kthread+0xed/0x120
  ? kthread_complete_and_exit+0x20/0x20
  ret_from_fork+0x22/0x30

Since the initialization of rx->link and rx->link_sta is rather convoluted
and duplicated in many places, clean it up by using a helper function to
set it.

Fixes: ccdde7c74ffd ("wifi: mac80211: properly implement MLO key handling")
Fixes: b320d6c456ff ("wifi: mac80211: use correct rx link_sta instead of default")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
v5: fix sdata link assignment, fix sdata when receiving on multiple interfaces
v4: fix regression in handling mgmt frames with AP_VLAN
v3: include crash log
v2: fix uninitialized variable
 net/mac80211/rx.c | 222 +++++++++++++++++++++-------------------------
 1 file changed, 99 insertions(+), 123 deletions(-)

Comments

Linux regression tracking (Thorsten Leemhuis) Jan. 2, 2023, 8:09 a.m. UTC | #1 
Hi, this is your Linux kernel regression tracker.

On 30.12.22 21:07, Felix Fietkau wrote:
> There are some codepaths that do not initialize rx->link_sta properly. This
> causes a crash in places which assume that rx->link_sta is valid if rx->sta
> is valid.
> One known instance is triggered by __ieee80211_rx_h_amsdu being called from
> fast-rx. It results in a crash like this one:

Many thx for working on this.

> [...]
> Fixes: ccdde7c74ffd ("wifi: mac80211: properly implement MLO key handling")
> Fixes: b320d6c456ff ("wifi: mac80211: use correct rx link_sta instead of default")
> Signed-off-by: Felix Fietkau <nbd@nbd.name>

Shouldn't this have a Cc: stable@vger.kernel.org to ensure it's
backported (no, Fixes: tags are not enough for that, as Greg
occasionally clarified).

And also a few link and reported-by tags to all the bug reports that
apparently are fixed by this change? These are the ones I'm aware of,
there might be more:

https://lore.kernel.org/linux-wireless/CAFktD2fRnSbNgWRRoGbQzG5_Mw7=zFJKTVBHS_3D+mNUYcv9hQ@mail.gmail.com/
https://bugzilla.kernel.org/show_bug.cgi?id=216839
https://bugzilla.kernel.org/show_bug.cgi?id=216844

This indicates that quite a few users are hit by problems this patch
fixes, hence from my point of view it obviously would be ideal if this
patch could make it to mainline quickly.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr

Did I miss something or do something stupid? Then reply and tell me:
https://linux-regtracking.leemhuis.info/about/#stupid

#regzbot ^backmonitor: https://bugzilla.kernel.org/show_bug.cgi?id=216844
diff mbox series

Patch

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 7e3ab6e1b28f..6ccc487bad7f 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -4049,6 +4049,58 @@  static void ieee80211_invoke_rx_handlers(struct ieee80211_rx_data *rx)
 #undef CALL_RXH
 }
 
+static bool
+ieee80211_rx_is_valid_sta_link_id(struct ieee80211_sta *sta, u8 link_id)
+{
+	if (!sta->mlo)
+		return false;
+
+	return !!(sta->valid_links & BIT(link_id));
+}
+
+static bool ieee80211_rx_data_set_link(struct ieee80211_rx_data *rx,
+				       u8 link_id)
+{
+	rx->link_id = link_id;
+	rx->link = rcu_dereference(rx->sdata->link[link_id]);
+
+	if (!rx->sta || !rx->sta->sta.mlo)
+		return rx->link;
+
+	if (!ieee80211_rx_is_valid_sta_link_id(&rx->sta->sta, link_id))
+		return false;
+
+	rx->link_sta = rcu_dereference(rx->sta->link[link_id]);
+
+	return rx->link && rx->link_sta;
+}
+
+static bool ieee80211_rx_data_set_sta(struct ieee80211_rx_data *rx,
+				      struct ieee80211_sta *pubsta,
+				      int link_id)
+{
+	struct sta_info *sta;
+
+	sta = container_of(pubsta, struct sta_info, sta);
+
+	rx->link_id = link_id;
+	rx->sta = sta;
+
+	if (sta) {
+		rx->local = sta->sdata->local;
+		if (!rx->sdata)
+			rx->sdata = sta->sdata;
+		rx->link_sta = &sta->deflink;
+	}
+
+	if (link_id < 0)
+		rx->link = &rx->sdata->deflink;
+	else if (!ieee80211_rx_data_set_link(rx, link_id))
+		return false;
+
+	return true;
+}
+
 /*
  * This function makes calls into the RX path, therefore
  * it has to be invoked under RCU read lock.
@@ -4057,16 +4109,19 @@  void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid)
 {
 	struct sk_buff_head frames;
 	struct ieee80211_rx_data rx = {
-		.sta = sta,
-		.sdata = sta->sdata,
-		.local = sta->local,
 		/* This is OK -- must be QoS data frame */
 		.security_idx = tid,
 		.seqno_idx = tid,
-		.link_id = -1,
 	};
 	struct tid_ampdu_rx *tid_agg_rx;
-	u8 link_id;
+	int link_id = -1;
+
+	/* FIXME: statistics won't be right with this */
+	if (sta->sta.valid_links)
+		link_id = ffs(sta->sta.valid_links) - 1;
+
+	if (!ieee80211_rx_data_set_sta(&rx, &sta->sta, link_id))
+		return;
 
 	tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
 	if (!tid_agg_rx)
@@ -4086,10 +4141,6 @@  void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid)
 		};
 		drv_event_callback(rx.local, rx.sdata, &event);
 	}
-	/* FIXME: statistics won't be right with this */
-	link_id = sta->sta.valid_links ? ffs(sta->sta.valid_links) - 1 : 0;
-	rx.link = rcu_dereference(sta->sdata->link[link_id]);
-	rx.link_sta = rcu_dereference(sta->link[link_id]);
 
 	ieee80211_rx_handlers(&rx, &frames);
 }
@@ -4105,7 +4156,6 @@  void ieee80211_mark_rx_ba_filtered_frames(struct ieee80211_sta *pubsta, u8 tid,
 		/* This is OK -- must be QoS data frame */
 		.security_idx = tid,
 		.seqno_idx = tid,
-		.link_id = -1,
 	};
 	int i, diff;
 
@@ -4116,10 +4166,8 @@  void ieee80211_mark_rx_ba_filtered_frames(struct ieee80211_sta *pubsta, u8 tid,
 
 	sta = container_of(pubsta, struct sta_info, sta);
 
-	rx.sta = sta;
-	rx.sdata = sta->sdata;
-	rx.link = &rx.sdata->deflink;
-	rx.local = sta->local;
+	if (!ieee80211_rx_data_set_sta(&rx, pubsta, -1))
+		return;
 
 	rcu_read_lock();
 	tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
@@ -4506,15 +4554,6 @@  void ieee80211_check_fast_rx_iface(struct ieee80211_sub_if_data *sdata)
 	mutex_unlock(&local->sta_mtx);
 }
 
-static bool
-ieee80211_rx_is_valid_sta_link_id(struct ieee80211_sta *sta, u8 link_id)
-{
-	if (!sta->mlo)
-		return false;
-
-	return !!(sta->valid_links & BIT(link_id));
-}
-
 static void ieee80211_rx_8023(struct ieee80211_rx_data *rx,
 			      struct ieee80211_fast_rx *fast_rx,
 			      int orig_len)
@@ -4625,7 +4664,6 @@  static bool ieee80211_invoke_fast_rx(struct ieee80211_rx_data *rx,
 	struct sk_buff *skb = rx->skb;
 	struct ieee80211_hdr *hdr = (void *)skb->data;
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
-	struct sta_info *sta = rx->sta;
 	int orig_len = skb->len;
 	int hdrlen = ieee80211_hdrlen(hdr->frame_control);
 	int snap_offs = hdrlen;
@@ -4637,7 +4675,6 @@  static bool ieee80211_invoke_fast_rx(struct ieee80211_rx_data *rx,
 		u8 da[ETH_ALEN];
 		u8 sa[ETH_ALEN];
 	} addrs __aligned(2);
-	struct link_sta_info *link_sta;
 	struct ieee80211_sta_rx_stats *stats;
 
 	/* for parallel-rx, we need to have DUP_VALIDATED, otherwise we write
@@ -4740,18 +4777,10 @@  static bool ieee80211_invoke_fast_rx(struct ieee80211_rx_data *rx,
  drop:
 	dev_kfree_skb(skb);
 
-	if (rx->link_id >= 0) {
-		link_sta = rcu_dereference(sta->link[rx->link_id]);
-		if (!link_sta)
-			return true;
-	} else {
-		link_sta = &sta->deflink;
-	}
-
 	if (fast_rx->uses_rss)
-		stats = this_cpu_ptr(link_sta->pcpu_rx_stats);
+		stats = this_cpu_ptr(rx->link_sta->pcpu_rx_stats);
 	else
-		stats = &link_sta->rx_stats;
+		stats = &rx->link_sta->rx_stats;
 
 	stats->dropped++;
 	return true;
@@ -4769,8 +4798,8 @@  static bool ieee80211_prepare_and_rx_handle(struct ieee80211_rx_data *rx,
 	struct ieee80211_local *local = rx->local;
 	struct ieee80211_sub_if_data *sdata = rx->sdata;
 	struct ieee80211_hdr *hdr = (void *)skb->data;
-	struct link_sta_info *link_sta = NULL;
-	struct ieee80211_link_data *link;
+	struct link_sta_info *link_sta = rx->link_sta;
+	struct ieee80211_link_data *link = rx->link;
 
 	rx->skb = skb;
 
@@ -4792,35 +4821,6 @@  static bool ieee80211_prepare_and_rx_handle(struct ieee80211_rx_data *rx,
 	if (!ieee80211_accept_frame(rx))
 		return false;
 
-	if (rx->link_id >= 0) {
-		link = rcu_dereference(rx->sdata->link[rx->link_id]);
-
-		/* we might race link removal */
-		if (!link)
-			return true;
-		rx->link = link;
-
-		if (rx->sta) {
-			rx->link_sta =
-				rcu_dereference(rx->sta->link[rx->link_id]);
-			if (!rx->link_sta)
-				return true;
-		}
-	} else {
-		if (rx->sta)
-			rx->link_sta = &rx->sta->deflink;
-
-		rx->link = &sdata->deflink;
-	}
-
-	if (unlikely(!is_multicast_ether_addr(hdr->addr1) &&
-		     rx->link_id >= 0 && rx->sta && rx->sta->sta.mlo)) {
-		link_sta = rcu_dereference(rx->sta->link[rx->link_id]);
-
-		if (WARN_ON_ONCE(!link_sta))
-			return true;
-	}
-
 	if (!consume) {
 		struct skb_shared_hwtstamps *shwt;
 
@@ -4840,7 +4840,7 @@  static bool ieee80211_prepare_and_rx_handle(struct ieee80211_rx_data *rx,
 		shwt->hwtstamp = skb_hwtstamps(skb)->hwtstamp;
 	}
 
-	if (unlikely(link_sta)) {
+	if (unlikely(rx->sta && rx->sta->sta.mlo)) {
 		/* translate to MLD addresses */
 		if (ether_addr_equal(link->conf->addr, hdr->addr1))
 			ether_addr_copy(hdr->addr1, rx->sdata->vif.addr);
@@ -4870,6 +4870,7 @@  static void __ieee80211_rx_handle_8023(struct ieee80211_hw *hw,
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 	struct ieee80211_fast_rx *fast_rx;
 	struct ieee80211_rx_data rx;
+	int link_id = -1;
 
 	memset(&rx, 0, sizeof(rx));
 	rx.skb = skb;
@@ -4886,12 +4887,8 @@  static void __ieee80211_rx_handle_8023(struct ieee80211_hw *hw,
 	if (!pubsta)
 		goto drop;
 
-	rx.sta = container_of(pubsta, struct sta_info, sta);
-	rx.sdata = rx.sta->sdata;
-
-	if (status->link_valid &&
-	    !ieee80211_rx_is_valid_sta_link_id(pubsta, status->link_id))
-		goto drop;
+	if (status->link_valid)
+		link_id = status->link_id;
 
 	/*
 	 * TODO: Should the frame be dropped if the right link_id is not
@@ -4900,19 +4897,8 @@  static void __ieee80211_rx_handle_8023(struct ieee80211_hw *hw,
 	 * link_id is used only for stats purpose and updating the stats on
 	 * the deflink is fine?
 	 */
-	if (status->link_valid)
-		rx.link_id = status->link_id;
-
-	if (rx.link_id >= 0) {
-		struct ieee80211_link_data *link;
-
-		link =  rcu_dereference(rx.sdata->link[rx.link_id]);
-		if (!link)
-			goto drop;
-		rx.link = link;
-	} else {
-		rx.link = &rx.sdata->deflink;
-	}
+	if (!ieee80211_rx_data_set_sta(&rx, pubsta, link_id))
+		goto drop;
 
 	fast_rx = rcu_dereference(rx.sta->fast_rx);
 	if (!fast_rx)
@@ -4930,6 +4916,8 @@  static bool ieee80211_rx_for_interface(struct ieee80211_rx_data *rx,
 {
 	struct link_sta_info *link_sta;
 	struct ieee80211_hdr *hdr = (void *)skb->data;
+	struct sta_info *sta;
+	int link_id = -1;
 
 	/*
 	 * Look up link station first, in case there's a
@@ -4939,24 +4927,19 @@  static bool ieee80211_rx_for_interface(struct ieee80211_rx_data *rx,
 	 */
 	link_sta = link_sta_info_get_bss(rx->sdata, hdr->addr2);
 	if (link_sta) {
-		rx->sta = link_sta->sta;
-		rx->link_id = link_sta->link_id;
+		sta = link_sta->sta;
+		link_id = link_sta->link_id;
 	} else {
 		struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 
-		rx->sta = sta_info_get_bss(rx->sdata, hdr->addr2);
-		if (rx->sta) {
-			if (status->link_valid &&
-			    !ieee80211_rx_is_valid_sta_link_id(&rx->sta->sta,
-							       status->link_id))
-				return false;
-
-			rx->link_id = status->link_valid ? status->link_id : -1;
-		} else {
-			rx->link_id = -1;
-		}
+		sta = sta_info_get_bss(rx->sdata, hdr->addr2);
+		if (status->link_valid)
+			link_id = status->link_id;
 	}
 
+	if (!ieee80211_rx_data_set_sta(rx, &sta->sta, link_id))
+		return false;
+
 	return ieee80211_prepare_and_rx_handle(rx, skb, consume);
 }
 
@@ -5015,19 +4998,15 @@  static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
 
 	if (ieee80211_is_data(fc)) {
 		struct sta_info *sta, *prev_sta;
-		u8 link_id = status->link_id;
+		int link_id = -1;
 
-		if (pubsta) {
-			rx.sta = container_of(pubsta, struct sta_info, sta);
-			rx.sdata = rx.sta->sdata;
+		if (status->link_valid)
+			link_id = status->link_id;
 
-			if (status->link_valid &&
-			    !ieee80211_rx_is_valid_sta_link_id(pubsta, link_id))
+		if (pubsta) {
+			if (!ieee80211_rx_data_set_sta(&rx, pubsta, link_id))
 				goto out;
 
-			if (status->link_valid)
-				rx.link_id = status->link_id;
-
 			/*
 			 * In MLO connection, fetch the link_id using addr2
 			 * when the driver does not pass link_id in status.
@@ -5045,7 +5024,7 @@  static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
 				if (!link_sta)
 					goto out;
 
-				rx.link_id = link_sta->link_id;
+				ieee80211_rx_data_set_link(&rx, link_sta->link_id);
 			}
 
 			if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
@@ -5061,30 +5040,27 @@  static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
 				continue;
 			}
 
-			if ((status->link_valid &&
-			     !ieee80211_rx_is_valid_sta_link_id(&prev_sta->sta,
-								link_id)) ||
-			    (!status->link_valid && prev_sta->sta.mlo))
+			rx.sdata = prev_sta->sdata;
+			if (!ieee80211_rx_data_set_sta(&rx, &prev_sta->sta,
+						       link_id))
+				goto out;
+
+			if (!status->link_valid && prev_sta->sta.mlo)
 				continue;
 
-			rx.link_id = status->link_valid ? link_id : -1;
-			rx.sta = prev_sta;
-			rx.sdata = prev_sta->sdata;
 			ieee80211_prepare_and_rx_handle(&rx, skb, false);
 
 			prev_sta = sta;
 		}
 
 		if (prev_sta) {
-			if ((status->link_valid &&
-			     !ieee80211_rx_is_valid_sta_link_id(&prev_sta->sta,
-								link_id)) ||
-			    (!status->link_valid && prev_sta->sta.mlo))
+			rx.sdata = prev_sta->sdata;
+			if (!ieee80211_rx_data_set_sta(&rx, &prev_sta->sta,
+						       link_id))
 				goto out;
 
-			rx.link_id = status->link_valid ? link_id : -1;
-			rx.sta = prev_sta;
-			rx.sdata = prev_sta->sdata;
+			if (!status->link_valid && prev_sta->sta.mlo)
+				goto out;
 
 			if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
 				return;