wifi: iwlwifi: mvm: fix double free on tx path.

We see kernel crashes and lockups and KASAN errors related to ax210
firmware crashes.  One of the KASAN dumps pointed at the tx path,
and it appears there is indeed a way to double-free an skb.

If iwl_mvm_tx_skb_sta returns non-zero, then the 'skb' sent into the
method will be freed.  But, in case where we build TSO skb buffer,
the skb may also be freed in error case.  So, return 0 in that particular
error case and do cleanup manually.

BUG: KASAN: use-after-free in __list_del_entry_valid+0x12/0x90
iwlwifi 0000:06:00.0: 0x00000000 | tsf hi
Read of size 8 at addr ffff88813cfa4ba0 by task btserver/9650

CPU: 4 PID: 9650 Comm: btserver Tainted: G        W         5.19.8+ #5
iwlwifi 0000:06:00.0: 0x00000000 | time gp1
Hardware name: Default string Default string/SKYBAY, BIOS 5.12 02/19/2019
Call Trace:
 <TASK>
 dump_stack_lvl+0x55/0x6d
 print_report.cold.12+0xf2/0x684
iwlwifi 0000:06:00.0: 0x1D0915A8 | time gp2
 ? __list_del_entry_valid+0x12/0x90
 kasan_report+0x8b/0x180
iwlwifi 0000:06:00.0: 0x00000001 | uCode revision type
 ? __list_del_entry_valid+0x12/0x90
 __list_del_entry_valid+0x12/0x90
iwlwifi 0000:06:00.0: 0x00000048 | uCode version major
 tcp_update_skb_after_send+0x5d/0x170
 __tcp_transmit_skb+0xb61/0x15c0
iwlwifi 0000:06:00.0: 0xDAA05125 | uCode version minor
 ? __tcp_select_window+0x490/0x490
iwlwifi 0000:06:00.0: 0x00000420 | hw version
 ? trace_kmalloc_node+0x29/0xd0
 ? __kmalloc_node_track_caller+0x12a/0x260
 ? memset+0x1f/0x40
 ? __build_skb_around+0x125/0x150
 ? __alloc_skb+0x1d4/0x220
 ? skb_zerocopy_clone+0x55/0x230
iwlwifi 0000:06:00.0: 0x00489002 | board version
 ? kmalloc_reserve+0x80/0x80
 ? rcu_read_lock_bh_held+0x60/0xb0
 tcp_write_xmit+0x3f1/0x24d0
iwlwifi 0000:06:00.0: 0x034E001C | hcmd
 ? __check_object_size+0x180/0x350
iwlwifi 0000:06:00.0: 0x24020000 | isr0
 tcp_sendmsg_locked+0x8a9/0x1520
iwlwifi 0000:06:00.0: 0x01400000 | isr1
 ? tcp_sendpage+0x50/0x50
iwlwifi 0000:06:00.0: 0x48F0000A | isr2
 ? lock_release+0xb9/0x400
 ? tcp_sendmsg+0x14/0x40
iwlwifi 0000:06:00.0: 0x00C3080C | isr3
 ? lock_downgrade+0x390/0x390
 ? do_raw_spin_lock+0x114/0x1d0
iwlwifi 0000:06:00.0: 0x00200000 | isr4
 ? rwlock_bug.part.2+0x50/0x50
iwlwifi 0000:06:00.0: 0x034A001C | last cmd Id
 ? rwlock_bug.part.2+0x50/0x50
 ? lockdep_hardirqs_on_prepare+0xe/0x200
iwlwifi 0000:06:00.0: 0x0000C2F0 | wait_event
 ? __local_bh_enable_ip+0x87/0xe0
 ? inet_send_prepare+0x220/0x220
iwlwifi 0000:06:00.0: 0x000000C4 | l2p_control
 tcp_sendmsg+0x22/0x40
 sock_sendmsg+0x5f/0x70
iwlwifi 0000:06:00.0: 0x00010034 | l2p_duration
 __sys_sendto+0x19d/0x250
iwlwifi 0000:06:00.0: 0x00000007 | l2p_mhvalid
 ? __ia32_sys_getpeername+0x40/0x40
iwlwifi 0000:06:00.0: 0x00000000 | l2p_addr_match
 ? rcu_read_lock_held_common+0x12/0x50
 ? rcu_read_lock_sched_held+0x5a/0xd0
 ? rcu_read_lock_bh_held+0xb0/0xb0
 ? rcu_read_lock_sched_held+0x5a/0xd0
 ? rcu_read_lock_sched_held+0x5a/0xd0
 ? lock_release+0xb9/0x400
 ? lock_downgrade+0x390/0x390
 ? ktime_get+0x64/0x130
 ? ktime_get+0x8d/0x130
 ? rcu_read_lock_held_common+0x12/0x50
 ? rcu_read_lock_sched_held+0x5a/0xd0
 ? rcu_read_lock_held_common+0x12/0x50
 ? rcu_read_lock_sched_held+0x5a/0xd0
 ? rcu_read_lock_bh_held+0xb0/0xb0
 ? rcu_read_lock_bh_held+0xb0/0xb0
 __x64_sys_sendto+0x6f/0x80
 do_syscall_64+0x34/0xb0
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f1d126e4531
Code: 00 00 00 00 0f 1f 44 00 00 f3 0f 1e fa 48 8d 05 35 80 0c 00 41 89 ca 8b 00 85 c0 75 1c 45 31 c9 45 31 c0 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 67 c3 66 0f 1f 44 00 00 55 48 83 ec 20 48 89
RSP: 002b:00007ffe21a679d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000000000000ffdc RCX: 00007f1d126e4531
RDX: 0000000000010000 RSI: 000000000374acf0 RDI: 0000000000000014
RBP: 00007ffe21a67ac0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000010
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
 </TASK>

Allocated by task 9650:
 kasan_save_stack+0x1c/0x40
 __kasan_slab_alloc+0x6d/0x90
 kmem_cache_alloc_node+0xf3/0x2b0
 __alloc_skb+0x191/0x220
 tcp_stream_alloc_skb+0x3f/0x330
 tcp_sendmsg_locked+0x67c/0x1520
 tcp_sendmsg+0x22/0x40
 sock_sendmsg+0x5f/0x70
 __sys_sendto+0x19d/0x250
 __x64_sys_sendto+0x6f/0x80
 do_syscall_64+0x34/0xb0
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 9650:
 kasan_save_stack+0x1c/0x40
 kasan_set_track+0x21/0x30
 kasan_set_free_info+0x20/0x30
 __kasan_slab_free+0x102/0x170
 kmem_cache_free+0xc8/0x3e0
 iwl_mvm_mac_itxq_xmit+0x124/0x270 [iwlmvm]
 ieee80211_queue_skb+0x874/0xd10 [mac80211]
 ieee80211_xmit_fast+0xf80/0x1180 [mac80211]
 __ieee80211_subif_start_xmit+0x287/0x680 [mac80211]
 ieee80211_subif_start_xmit+0xcd/0x730 [mac80211]
 dev_hard_start_xmit+0xf6/0x420
 __dev_queue_xmit+0x165b/0x1b50
 ip_finish_output2+0x66e/0xfb0
 __ip_finish_output+0x487/0x6d0
 ip_output+0x11c/0x350
 __ip_queue_xmit+0x36b/0x9d0
 __tcp_transmit_skb+0xb35/0x15c0
 tcp_write_xmit+0x3f1/0x24d0
 tcp_sendmsg_locked+0x8a9/0x1520
 tcp_sendmsg+0x22/0x40
 sock_sendmsg+0x5f/0x70
 __sys_sendto+0x19d/0x250
 __x64_sys_sendto+0x6f/0x80
 do_syscall_64+0x34/0xb0
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88813cfa4b40
 which belongs to the cache skbuff_fclone_cache of size 472
The buggy address is located 96 bytes inside of
 472-byte region [ffff88813cfa4b40, ffff88813cfa4d18)

The buggy address belongs to the physical page:
page:ffffea0004f3e900 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88813cfa6c40 pfn:0x13cfa4
head:ffffea0004f3e900 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x5fff8000010200(slab|head|node=0|zone=2|lastcpupid=0x3fff)
raw: 005fff8000010200 ffffea0004656b08 ffffea0008e8cf08 ffff8881081a5240
raw: ffff88813cfa6c40 0000000000170015 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88813cfa4a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88813cfa4b00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff88813cfa4b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88813cfa4c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88813cfa4c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fixes: 08f7d8b69aaf ("iwlwifi: mvm: bring back mvm GSO code")
Link: https://lore.kernel.org/linux-wireless/20220928193057.16132-1-greearb@candelatech.com/
Tested-by: Amol Jawale <amol.jawale@candelatech.com>
Signed-off-by: Ben Greear <greearb@candelatech.com>
Link: https://lore.kernel.org/r/20221123225313.21b1ee31d666.I3b3ba184433dd2a544d91eeeda29b467021824ae@changeid
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tx.c b/drivers/net/wireless/intel/iwlwifi/mvm/tx.c
index f460332333a7..fadaa683a416 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/tx.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tx.c
@@ -1215,6 +1215,7 @@ int iwl_mvm_tx_skb_sta(struct iwl_mvm *mvm, struct sk_buff *skb,
 	struct sk_buff_head mpdus_skbs;
 	unsigned int payload_len;
 	int ret;
+	struct sk_buff *orig_skb = skb;
 
 	if (WARN_ON_ONCE(!mvmsta))
 		return -1;
@@ -1247,8 +1248,17 @@ int iwl_mvm_tx_skb_sta(struct iwl_mvm *mvm, struct sk_buff *skb,
 
 		ret = iwl_mvm_tx_mpdu(mvm, skb, &info, sta);
 		if (ret) {
+			/* Free skbs created as part of TSO logic that have not yet been dequeued */
 			__skb_queue_purge(&mpdus_skbs);
-			return ret;
+			/* skb here is not necessarily same as skb that entered this method,
+			 * so free it explicitly.
+			 */
+			if (skb == orig_skb)
+				ieee80211_free_txskb(mvm->hw, skb);
+			else
+				kfree_skb(skb);
+			/* there was error, but we consumed skb one way or another, so return 0 */
+			return 0;
 		}
 	}