Subject: Re: general protection fault in ieee80211_chanctx_num_assigned

From: syzbot <[email-masked]>
Date: Sun, 22 Nov 2020 05:56:15 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    a349e4c6 Merge tag 'xfs-5.10-fixes-7' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=144e1e99500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=330f3436df12fd44
dashboard link: https://syzkaller.appspot.com/bug?extid=00ce7332120071df39b1
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=153140a5500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=179bf835500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

general protection fault, probably for non-canonical address 0xfbd59c0000000020: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107]
CPU: 1 PID: 8531 Comm: syz-executor169 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ieee80211_chanctx_num_assigned+0xb1/0x140 net/mac80211/chan.c:21
Code: a8 f6 ff ff 48 39 c5 74 3b 49 bd 00 00 00 00 00 fc ff df e8 c1 91 1b f9 48 8d bb 58 09 00 00 41 83 c4 01 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 75 68 48 8b 83 58 09 00 00 48 8d 98 a8 f6 ff ff 48
RSP: 0018:ffffc9000169f330 EFLAGS: 00010a02
RAX: 1bd5a00000000020 RBX: deacfffffffff7a8 RCX: ffffffff88549e6b
RDX: ffff888011c8b480 RSI: ffffffff88549e0f RDI: dead000000000100
RBP: ffff8880130ca720 R08: 0000000000000000 R09: ffffffff8cecb9cf
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
R13: dffffc0000000000 R14: ffff8880130ca700 R15: 0000000000000000
FS:  000000000087d940(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000006d3090 CR3: 000000001c20a000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ieee80211_assign_vif_chanctx+0x7b8/0x1230 net/mac80211/chan.c:690
 __ieee80211_vif_release_channel+0x236/0x430 net/mac80211/chan.c:1557
 ieee80211_vif_release_channel+0x117/0x220 net/mac80211/chan.c:1771
 ieee80211_ibss_disconnect+0x44e/0x7b0 net/mac80211/ibss.c:735
 ieee80211_ibss_leave+0x12/0xe0 net/mac80211/ibss.c:1871
 rdev_leave_ibss net/wireless/rdev-ops.h:545 [inline]
 __cfg80211_leave_ibss+0x19a/0x4c0 net/wireless/ibss.c:212
 cfg80211_leave_ibss+0x57/0x80 net/wireless/ibss.c:230
 cfg80211_change_iface+0x855/0xef0 net/wireless/util.c:1012
 nl80211_set_interface+0x65c/0x8d0 net/wireless/nl80211.c:3789
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739
 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4429b9
Code: e8 bc fd 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd820d0a58 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004429b9
RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000004
RBP: 000000000000fbef R08: 00000000004035b0 R09: 00000000004035b0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000403520
R13: 00000000004035b0 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 4cedfcb59a8efe47 ]---
RIP: 0010:ieee80211_chanctx_num_assigned+0xb1/0x140 net/mac80211/chan.c:21
Code: a8 f6 ff ff 48 39 c5 74 3b 49 bd 00 00 00 00 00 fc ff df e8 c1 91 1b f9 48 8d bb 58 09 00 00 41 83 c4 01 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 75 68 48 8b 83 58 09 00 00 48 8d 98 a8 f6 ff ff 48
RSP: 0018:ffffc9000169f330 EFLAGS: 00010a02
RAX: 1bd5a00000000020 RBX: deacfffffffff7a8 RCX: ffffffff88549e6b
RDX: ffff888011c8b480 RSI: ffffffff88549e0f RDI: dead000000000100
RBP: ffff8880130ca720 R08: 0000000000000000 R09: ffffffff8cecb9cf
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
R13: dffffc0000000000 R14: ffff8880130ca700 R15: 0000000000000000
FS:  000000000087d940(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efedefa7000 CR3: 000000001c20a000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400