[syzbot] [wireless?] BUG: unable to handle kernel paging request in trace_event_raw_event_drv_net_setup_tc

[syzbot] [wireless?] BUG: unable to handle kernel paging request in trace_event_raw_event_drv_net_setup_tc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    8ba098e6b6ff Merge tag 'v7.2-rc5-smb3-client-fixes' of git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f84c9e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=f1ba58d6b55abd13239e
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/db1d2f27959e/disk-8ba098e6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2eacbf7835c3/vmlinux-8ba098e6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/de833d39bd28/bzImage-8ba098e6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com

BUG: unable to handle page fault for address: fffffffffffffc10
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD e997067 P4D e997067 PUD e999067 PMD 0 
Oops: Oops: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 15892 Comm: syz.5.2483 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:strnlen+0x4b/0x80 lib/string.c:414
Code: 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 0f b6 14 1a 38 ca 7f 04 84 d2 75 15 <80> 38 00 75 d9 4c 29 e0 48 83 c4 08 5b 5d 41 5c e9 40 87 07 00 48
RSP: 0018:ffffc900071ef120 EFLAGS: 00010246
RAX: fffffffffffffc10 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000010 RDI: fffffffffffffc10
RBP: fffffffffffffc20 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffc10
R13: ffff88801bcc3e00 R14: 0000000000000006 R15: 0000000000000010
FS:  00007faa1ab866c0(0000) GS:ffff888123dda000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffc10 CR3: 0000000025e0b000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 strnlen include/linux/fortify-string.h:183 [inline]
 __fortify_strlen include/linux/fortify-string.h:219 [inline]
 trace_event_get_offsets_drv_net_setup_tc net/mac80211/trace.h:2539 [inline]
 do_trace_event_raw_event_drv_net_setup_tc net/mac80211/trace.h:2539 [inline]
 trace_event_raw_event_drv_net_setup_tc+0x100/0x5d0 net/mac80211/trace.h:2539
 __do_trace_drv_net_setup_tc net/mac80211/trace.h:2539 [inline]
 trace_drv_net_setup_tc net/mac80211/trace.h:2539 [inline]
 drv_net_setup_tc net/mac80211/driver-ops.h:1706 [inline]
 ieee80211_netdev_setup_tc+0x2c6/0x3e0 net/mac80211/iface.c:938
 tcf_block_offload_cmd.isra.0+0x1c4/0x310 net/sched/cls_api.c:838
 tcf_block_offload_bind net/sched/cls_api.c:875 [inline]
 tcf_block_get_ext+0x7ed/0x1950 net/sched/cls_api.c:1498
 tcf_block_get+0xa8/0x100 net/sched/cls_api.c:1543
 hfsc_init_qdisc+0x154/0x420 net/sched/sch_hfsc.c:1413
 qdisc_create+0x47b/0x1060 net/sched/sch_api.c:1337
 __tc_modify_qdisc net/sched/sch_api.c:1771 [inline]
 tc_modify_qdisc+0xdcf/0x2120 net/sched/sch_api.c:1835
 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:7085
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738
 __sys_sendmsg+0x160/0x210 net/socket.c:2770
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faa19d9e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007faa1ab86028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007faa1a025fa0 RCX: 00007faa19d9e019
RDX: 0000000000000000 RSI: 00002000000008c0 RDI: 0000000000000004
RBP: 00007faa19e3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007faa1a026038 R14: 00007faa1a025fa0 R15: 00007ffd20378ea8
 </TASK>
Modules linked in:
CR2: fffffffffffffc10
---[ end trace 0000000000000000 ]---
RIP: 0010:strnlen+0x4b/0x80 lib/string.c:414
Code: 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 0f b6 14 1a 38 ca 7f 04 84 d2 75 15 <80> 38 00 75 d9 4c 29 e0 48 83 c4 08 5b 5d 41 5c e9 40 87 07 00 48
RSP: 0018:ffffc900071ef120 EFLAGS: 00010246
RAX: fffffffffffffc10 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000010 RDI: fffffffffffffc10
RBP: fffffffffffffc20 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffc10
R13: ffff88801bcc3e00 R14: 0000000000000006 R15: 0000000000000010
FS:  00007faa1ab866c0(0000) GS:ffff888123dda000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffc10 CR3: 0000000025e0b000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	49 89 fc             	mov    %rdi,%r12
   3:	48 89 f8             	mov    %rdi,%rax
   6:	eb 09                	jmp    0x11
   8:	48 83 c0 01          	add    $0x1,%rax
   c:	48 39 e8             	cmp    %rbp,%rax
   f:	74 1e                	je     0x2f
  11:	48 89 c2             	mov    %rax,%rdx
  14:	48 89 c1             	mov    %rax,%rcx
  17:	48 c1 ea 03          	shr    $0x3,%rdx
  1b:	83 e1 07             	and    $0x7,%ecx
  1e:	0f b6 14 1a          	movzbl (%rdx,%rbx,1),%edx
  22:	38 ca                	cmp    %cl,%dl
  24:	7f 04                	jg     0x2a
  26:	84 d2                	test   %dl,%dl
  28:	75 15                	jne    0x3f
* 2a:	80 38 00             	cmpb   $0x0,(%rax) <-- trapping instruction
  2d:	75 d9                	jne    0x8
  2f:	4c 29 e0             	sub    %r12,%rax
  32:	48 83 c4 08          	add    $0x8,%rsp
  36:	5b                   	pop    %rbx
  37:	5d                   	pop    %rbp
  38:	41 5c                	pop    %r12
  3a:	e9 40 87 07 00       	jmp    0x7877f
  3f:	48                   	rex.W


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[PATCH] wifi: mac80211: guard drv_net_setup_tc() against unbound AP_VLAN sdata

[Ayushman Rout]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

syzbot reports a NULL/invalid pointer dereference in
trace_event_raw_event_drv_net_setup_tc(), reached via
ieee80211_netdev_setup_tc() -> drv_net_setup_tc().

drv_net_setup_tc() calls get_bss_sdata(sdata) unconditionally. For an
NL80211_IFTYPE_AP_VLAN interface this does
container_of(sdata->bss, ...), but sdata->bss is only linked
opportunistically at interface-add time when a matching same-address
AP interface exists - it is not enforced, so an AP_VLAN interface can
be fully created and registered with sdata->bss left NULL.
container_of() on NULL yields a small invalid pointer rather than
NULL, which the trace_drv_net_setup_tc tracepoint then dereferences
to read the interface name.

Guard against an unbound AP_VLAN sdata before calling
get_bss_sdata(), matching the WARN_ON_ONCE(!bss) precondition already
used for this same relationship in sta_info.c. Also add
check_sdata_in_driver(), used by the neighboring
drv_net_fill_forward_path() but missing here.

The underlying gap in ieee80211_if_add() - AP_VLAN creation not
requiring a bound bss - is not fixed here; other get_bss_sdata()
callers may share the exposure.

Fixes: 61587f1556fe ("wifi: mac80211: add support for letting drivers register tc offload support")
Reported-by: syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f1ba58d6b55abd13239e
Signed-off-by: Ayushman Rout <ayushmanrout27@gmail.com>
---
 net/mac80211/driver-ops.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index f1c0b87fddd5..ecfdb51152f4 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -1702,7 +1702,23 @@ static inline int drv_net_setup_tc(struct ieee80211_local *local,
 
 	might_sleep();
 
+	/*
+	 * An AP_VLAN interface created without a matching, same-address
+	 * AP interface present never gets sdata->bss populated (see the
+	 * interface-add validation in iface.c, which links bss only
+	 * opportunistically and does not require it). Such an sdata is
+	 * not safe to pass through get_bss_sdata(): container_of() on a
+	 * NULL sdata->bss yields a small invalid pointer, which the
+	 * tracepoint below then dereferences to read the interface name,
+	 * causing a crash.
+	 */
+	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->bss)
+		return -EIO;
+
 	sdata = get_bss_sdata(sdata);
+	if (!check_sdata_in_driver(sdata))
+		return -EIO;
+
 	trace_drv_net_setup_tc(local, sdata, type);
 	if (local->ops->net_setup_tc)
 		ret = local->ops->net_setup_tc(&local->hw, &sdata->vif, dev,
-- 
2.54.0

Re: [PATCH] wifi: mac80211: guard drv_net_setup_tc() against unbound AP_VLAN sdata

[syzbot]

> #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

This crash does not have a reproducer. I cannot test it.

>
> syzbot reports a NULL/invalid pointer dereference in
> trace_event_raw_event_drv_net_setup_tc(), reached via
> ieee80211_netdev_setup_tc() -> drv_net_setup_tc().
>
> drv_net_setup_tc() calls get_bss_sdata(sdata) unconditionally. For an
> NL80211_IFTYPE_AP_VLAN interface this does
> container_of(sdata->bss, ...), but sdata->bss is only linked
> opportunistically at interface-add time when a matching same-address
> AP interface exists - it is not enforced, so an AP_VLAN interface can
> be fully created and registered with sdata->bss left NULL.
> container_of() on NULL yields a small invalid pointer rather than
> NULL, which the trace_drv_net_setup_tc tracepoint then dereferences
> to read the interface name.
>
> Guard against an unbound AP_VLAN sdata before calling
> get_bss_sdata(), matching the WARN_ON_ONCE(!bss) precondition already
> used for this same relationship in sta_info.c. Also add
> check_sdata_in_driver(), used by the neighboring
> drv_net_fill_forward_path() but missing here.
>
> The underlying gap in ieee80211_if_add() - AP_VLAN creation not
> requiring a bound bss - is not fixed here; other get_bss_sdata()
> callers may share the exposure.
>
> Fixes: 61587f1556fe ("wifi: mac80211: add support for letting drivers register tc offload support")
> Reported-by: syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=f1ba58d6b55abd13239e
> Signed-off-by: Ayushman Rout <ayushmanrout27@gmail.com>
> ---
>  net/mac80211/driver-ops.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
> index f1c0b87fddd5..ecfdb51152f4 100644
> --- a/net/mac80211/driver-ops.h
> +++ b/net/mac80211/driver-ops.h
> @@ -1702,7 +1702,23 @@ static inline int drv_net_setup_tc(struct ieee80211_local *local,
>  
>  	might_sleep();
>  
> +	/*
> +	 * An AP_VLAN interface created without a matching, same-address
> +	 * AP interface present never gets sdata->bss populated (see the
> +	 * interface-add validation in iface.c, which links bss only
> +	 * opportunistically and does not require it). Such an sdata is
> +	 * not safe to pass through get_bss_sdata(): container_of() on a
> +	 * NULL sdata->bss yields a small invalid pointer, which the
> +	 * tracepoint below then dereferences to read the interface name,
> +	 * causing a crash.
> +	 */
> +	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->bss)
> +		return -EIO;
> +
>  	sdata = get_bss_sdata(sdata);
> +	if (!check_sdata_in_driver(sdata))
> +		return -EIO;
> +
>  	trace_drv_net_setup_tc(local, sdata, type);
>  	if (local->ops->net_setup_tc)
>  		ret = local->ops->net_setup_tc(&local->hw, &sdata->vif, dev,
> -- 
> 2.54.0
>

[PATCH] wifi: mac80211: guard drv_net_setup_tc() against unbound AP_VLAN sdata

[Ayushman Rout]

syzbot reports a NULL/invalid pointer dereference in
trace_event_raw_event_drv_net_setup_tc(), reached via
ieee80211_netdev_setup_tc() -> drv_net_setup_tc().

drv_net_setup_tc() calls get_bss_sdata(sdata) unconditionally. For an
NL80211_IFTYPE_AP_VLAN interface this does
container_of(sdata->bss, ...), but sdata->bss is only linked
opportunistically at interface-add time when a matching same-address
AP interface exists - it is not enforced, so an AP_VLAN interface can
be fully created and registered with sdata->bss left NULL.
container_of() on NULL yields a small invalid pointer rather than
NULL, which the trace_drv_net_setup_tc tracepoint then dereferences
to read the interface name.

Guard against an unbound AP_VLAN sdata before calling
get_bss_sdata(), matching the WARN_ON_ONCE(!bss) precondition already
used for this same relationship in sta_info.c. Also add
check_sdata_in_driver(), used by the neighboring
drv_net_fill_forward_path() but missing here.

The underlying gap in ieee80211_if_add() - AP_VLAN creation not
requiring a bound bss - is not fixed here; other get_bss_sdata()
callers may share the exposure.

Fixes: 61587f1556fe ("wifi: mac80211: add support for letting drivers register tc offload support")
Reported-by: syzbot+f1ba58d6b55abd13239e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f1ba58d6b55abd13239e
Signed-off-by: Ayushman Rout <ayushmanrout27@gmail.com>
---
 net/mac80211/driver-ops.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index f1c0b87fddd5..ecfdb51152f4 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -1702,7 +1702,23 @@ static inline int drv_net_setup_tc(struct ieee80211_local *local,
 
 	might_sleep();
 
+	/*
+	 * An AP_VLAN interface created without a matching, same-address
+	 * AP interface present never gets sdata->bss populated (see the
+	 * interface-add validation in iface.c, which links bss only
+	 * opportunistically and does not require it). Such an sdata is
+	 * not safe to pass through get_bss_sdata(): container_of() on a
+	 * NULL sdata->bss yields a small invalid pointer, which the
+	 * tracepoint below then dereferences to read the interface name,
+	 * causing a crash.
+	 */
+	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->bss)
+		return -EIO;
+
 	sdata = get_bss_sdata(sdata);
+	if (!check_sdata_in_driver(sdata))
+		return -EIO;
+
 	trace_drv_net_setup_tc(local, sdata, type);
 	if (local->ops->net_setup_tc)
 		ret = local->ops->net_setup_tc(&local->hw, &sdata->vif, dev,
-- 
2.54.0