[syzbot] [mm?] WARNING in unlink_anon_vmas (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b775e489bec7 Add linux-next specific files for 20260114
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15dbc444580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2dcf53f0a51185
dashboard link: https://syzkaller.appspot.com/bug?extid=c27fa543e10a45d4e149
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17070522580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1683f99a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5e077e7eafdc/disk-b775e489.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ea69aef6ee56/vmlinux-b775e489.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b8b6986280d1/bzImage-b775e489.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c27fa5...@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007f16655e5fa0 R14: 00007f16655e5fa0 R15: 0000000000000002
</TASK>
------------[ cut here ]------------
WARNING: mm/rmap.c:480 at unlink_anon_vmas+0x701/0x730 mm/rmap.c:480, CPU#0: syz.0.20/5987
Modules linked in:
CPU: 0 UID: 0 PID: 5987 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:unlink_anon_vmas+0x701/0x730 mm/rmap.c:480
Code: ac ff 48 83 c4 40 5b 41 5c 41 5d 41 5e 41 5f 5d e9 84 df 56 09 cc e8 8e ed ac ff 90 0f 0b 90 e9 e2 f9 ff ff e8 80 ed ac ff 90 <0f> 0b 90 eb d3 48 c7 c1 10 ab c4 8f 80 e1 07 80 c1 03 38 c1 0f 8c
RSP: 0018:ffffc900033676c0 EFLAGS: 00010293
RAX: ffffffff821460b0 RBX: dffffc0000000000 RCX: ffff88802a773c80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff8fc47af7 R09: 1ffffffff1f88f5e
R10: dffffc0000000000 R11: fffffbfff1f88f5f R12: 1ffff110062fbaa8
R13: ffff888027aad900 R14: ffff8880317dd510 R15: ffff8880317dd530
FS: 0000555592787500(0000) GS:ffff8881259ad000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f166526615a CR3: 000000002f0cc000 CR4: 00000000003526f0
Call Trace:
<TASK>
anon_vma_fork+0x4b9/0x500 mm/rmap.c:438
dup_mmap+0x954/0x1b80 mm/mmap.c:1790
dup_mm kernel/fork.c:1529 [inline]
copy_mm+0x13c/0x4b0 kernel/fork.c:1581
copy_process+0x1812/0x3ba0 kernel/fork.c:2218
kernel_clone+0x21e/0x820 kernel/fork.c:2648
__do_sys_clone3 kernel/fork.c:2950 [inline]
__se_sys_clone3+0x256/0x2d0 kernel/fork.c:2929
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f166538f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe55f4df08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b3
RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f166538f749
RDX: 00007ffe55f4df20 RSI: 0000000000000058 RDI: 00007ffe55f4df20
RBP: 00007ffe55f4e090 R08: 0000000000000000 R09: 0000000000000058
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007f16655e5fa0 R14: 00007f16655e5fa0 R15: 0000000000000002
</TASK>


---
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[syzbot]

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***

Subject: [PATCH] mm/rmap: fix unlink_anon_vmas() handling of error case from anon_vma_fork
Author: karti...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master

When anon_vma_fork() encounters a memory allocation failure after
anon_vma_clone() has succeeded, unlink_anon_vmas() is called with
vma->anon_vma being NULL but the anon_vma_chain populated with entries
that are present in the anon_vma interval trees.

This happens in the following sequence:
1. anon_vma_clone() succeeds, populating vma->anon_vma_chain and
inserting entries into interval trees
2. maybe_reuse_anon_vma() does not set vma->anon_vma because reuse
conditions are not met (common case for active processes)
3. anon_vma_alloc() or anon_vma_chain_alloc() fails due to memory
pressure
4. Error path invokes unlink_anon_vmas() with vma->anon_vma == NULL

The existing code triggered VM_WARN_ON_ONCE and returned without
performing cleanup, leaving entries in interval trees and causing
memory leaks.

Fix this by detecting the condition and properly cleaning up:
- Iterate through the populated chain
- Lock each anon_vma
- Remove entries from interval trees
- Unlock and free chain entries

This prevents both the warning and the resource leaks.

Reported-by: syzbot+c27fa5...@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=c27fa543e10a45d4e149
Signed-off-by: Deepanshu Kartikey <karti...@gmail.com>
---
mm/rmap.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index f13480cb9f2e..acc8df6ad4a7 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -477,7 +477,31 @@ void unlink_anon_vmas(struct vm_area_struct *vma)

/* Unfaulted is a no-op. */
if (!active_anon_vma) {
- VM_WARN_ON_ONCE(!list_empty(&vma->anon_vma_chain));
+ /*
+ * Handle anon_vma_fork() error path where anon_vma_clone()
+ * succeeded and populated the chain (with entries in interval
+ * trees), but maybe_reuse_anon_vma() didn't set vma->anon_vma
+ * because reuse conditions weren't met, and a later allocation
+ * failed before we could allocate and assign a new anon_vma.
+ *
+ * We must properly remove entries from interval trees before
+ * freeing to avoid leaving dangling pointers.
+ */
+ if (!list_empty(&vma->anon_vma_chain)) {
+ struct anon_vma_chain *avc, *next;
+
+ list_for_each_entry_safe(avc, next, &vma->anon_vma_chain,
+ same_vma) {
+ struct anon_vma *anon_vma = avc->anon_vma;
+
+ anon_vma_lock_write(anon_vma);
+ anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
+ anon_vma_unlock_write(anon_vma);
+ list_del(&avc->same_vma);
+ anon_vma_chain_free(avc);
+ }
+ }
+
return;
}

--
2.43.0

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

SYZFAIL: failed to recv rpc

SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)


Warning: Permanently added '10.128.1.53' (ED25519) to the list of known hosts.
2026/01/18 09:20:01 parsed 1 programs
[ 77.901035][ T5828] cgroup: Unknown subsys name 'net'
[ 78.037193][ T5828] cgroup: Unknown subsys name 'cpuset'
[ 78.046859][ T5828] cgroup: Unknown subsys name 'rlimit'
Setting up swapspace version 1, size = 127995904 bytes
[ 79.512011][ T5828] Adding 124996k swap on ./swap-file. Priority:0 extents:1 across:124996k
[ 82.341391][ T5835] soft_limit_in_bytes is deprecated and will be removed. Please report your usecase to linu...@kvack.org if you depend on this functionality.
[ 83.758436][ T1015] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[ 83.774306][ T1015] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[ 83.821559][ T1015] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[ 83.831495][ T1015] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[ 85.270179][ T5897] chnl_net:caif_netlink_parms(): no params data found
[ 85.377098][ T5897] bridge0: port 1(bridge_slave_0) entered blocking state
[ 85.385837][ T5897] bridge0: port 1(bridge_slave_0) entered disabled state
[ 85.393932][ T5897] bridge_slave_0: entered allmulticast mode
[ 85.406735][ T5897] bridge_slave_0: entered promiscuous mode
[ 85.417915][ T5897] bridge0: port 2(bridge_slave_1) entered blocking state
[ 85.425327][ T5897] bridge0: port 2(bridge_slave_1) entered disabled state
[ 85.433157][ T5897] bridge_slave_1: entered allmulticast mode
[ 85.440912][ T5897] bridge_slave_1: entered promiscuous mode
[ 85.474547][ T5897] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[ 85.487901][ T5897] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[ 85.518305][ T5897] team0: Port device team_slave_0 added
[ 85.527422][ T5897] team0: Port device team_slave_1 added
[ 85.555868][ T5897] batman_adv: batadv0: Adding interface: batadv_slave_0
[ 85.562935][ T5897] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[ 85.590621][ T5897] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[ 85.605927][ T5897] batman_adv: batadv0: Adding interface: batadv_slave_1
[ 85.613503][ T5897] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[ 85.639963][ T5897] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[ 85.684487][ T5897] hsr_slave_0: entered promiscuous mode
[ 85.691316][ T5897] hsr_slave_1: entered promiscuous mode
[ 85.859484][ T5897] netdevsim netdevsim0 netdevsim0: renamed from eth0
[ 85.874651][ T5897] netdevsim netdevsim0 netdevsim1: renamed from eth1
[ 85.886048][ T5897] netdevsim netdevsim0 netdevsim2: renamed from eth2
[ 85.897250][ T5897] netdevsim netdevsim0 netdevsim3: renamed from eth3
[ 85.977012][ T5897] 8021q: adding VLAN 0 to HW filter on device bond0
[ 85.999505][ T5897] 8021q: adding VLAN 0 to HW filter on device team0
[ 86.015481][ T48] bridge0: port 1(bridge_slave_0) entered blocking state
[ 86.022966][ T48] bridge0: port 1(bridge_slave_0) entered forwarding state
[ 86.043961][ T138] bridge0: port 2(bridge_slave_1) entered blocking state
[ 86.051117][ T138] bridge0: port 2(bridge_slave_1) entered forwarding state
[ 86.228809][ T5897] 8021q: adding VLAN 0 to HW filter on device batadv0
[ 86.286274][ T5897] veth0_vlan: entered promiscuous mode
[ 86.299783][ T5897] veth1_vlan: entered promiscuous mode
[ 86.329644][ T5897] veth0_macvtap: entered promiscuous mode
[ 86.343054][ T5897] veth1_macvtap: entered promiscuous mode
[ 86.363147][ T5897] batman_adv: batadv0: Interface activated: batadv_slave_0
[ 86.380112][ T5897] batman_adv: batadv0: Interface activated: batadv_slave_1
[ 86.399133][ T48] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[ 86.410010][ T48] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[ 86.421091][ T48] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[ 86.432173][ T48] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[ 86.598062][ T5150] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[ 86.607913][ T5150] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[ 86.609158][ T138] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[ 86.623754][ T5150] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[ 86.636311][ T5150] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[ 86.645064][ T5150] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[ 86.691225][ T138] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[ 86.743066][ T138] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[ 86.808471][ T138] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
2026/01/18 09:20:13 executed programs: 0
[ 87.897627][ T5150] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[ 87.907311][ T5150] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[ 87.917067][ T5150] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[ 87.926516][ T5150] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[ 87.934931][ T5150] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[ 88.101828][ T5940] chnl_net:caif_netlink_parms(): no params data found
[ 88.175963][ T5940] bridge0: port 1(bridge_slave_0) entered blocking state
[ 88.183508][ T5940] bridge0: port 1(bridge_slave_0) entered disabled state
[ 88.190988][ T5940] bridge_slave_0: entered allmulticast mode
[ 88.198822][ T5940] bridge_slave_0: entered promiscuous mode
[ 88.214722][ T5940] bridge0: port 2(bridge_slave_1) entered blocking state
[ 88.222402][ T5940] bridge0: port 2(bridge_slave_1) entered disabled state
[ 88.229826][ T5940] bridge_slave_1: entered allmulticast mode
[ 88.237116][ T5940] bridge_slave_1: entered promiscuous mode
[ 88.272871][ T5940] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[ 88.285334][ T5940] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[ 88.320146][ T5940] team0: Port device team_slave_0 added
[ 88.329176][ T5940] team0: Port device team_slave_1 added
[ 88.356327][ T5940] batman_adv: batadv0: Adding interface: batadv_slave_0
[ 88.363729][ T5940] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[ 88.390930][ T5940] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[ 88.404526][ T5940] batman_adv: batadv0: Adding interface: batadv_slave_1
[ 88.411643][ T5940] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[ 88.440029][ T5940] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[ 88.488754][ T5940] hsr_slave_0: entered promiscuous mode
[ 88.495800][ T5940] hsr_slave_1: entered promiscuous mode
[ 88.502287][ T5940] debugfs: 'hsr0' already exists in 'hsr'
[ 88.509149][ T5940] Cannot create hsr debugfs directory
[ 89.269277][ T138] bridge_slave_1: left allmulticast mode
[ 89.276040][ T138] bridge_slave_1: left promiscuous mode
[ 89.282780][ T138] bridge0: port 2(bridge_slave_1) entered disabled state
[ 89.296292][ T138] bridge_slave_0: left allmulticast mode
[ 89.301959][ T138] bridge_slave_0: left promiscuous mode
[ 89.308602][ T138] bridge0: port 1(bridge_slave_0) entered disabled state
[ 89.628117][ T138] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[ 89.640101][ T138] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[ 89.656329][ T138] bond0 (unregistering): Released all slaves
[ 89.792085][ T138] hsr_slave_0: left promiscuous mode
[ 89.798862][ T138] hsr_slave_1: left promiscuous mode
[ 89.805585][ T138] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[ 89.823607][ T138] batman_adv: batadv0: Removing interface: batadv_slave_0
[ 89.845653][ T138] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[ 89.857800][ T138] batman_adv: batadv0: Removing interface: batadv_slave_1
[ 89.886296][ T138] veth1_macvtap: left promiscuous mode
[ 89.894314][ T138] veth0_macvtap: left promiscuous mode
[ 89.900282][ T138] veth1_vlan: left promiscuous mode
[ 89.906625][ T138] veth0_vlan: left promiscuous mode
[ 89.974848][ T5150] Bluetooth: hci0: command tx timeout
[ 90.443879][ T138] team0 (unregistering): Port device team_slave_1 removed
[ 90.484332][ T138] team0 (unregistering): Port device team_slave_0 removed
[ 91.120268][ T5940] netdevsim netdevsim0 netdevsim0: renamed from eth0
[ 91.141856][ T5940] netdevsim netdevsim0 netdevsim1: renamed from eth1
[ 91.156300][ T5940] netdevsim netdevsim0 netdevsim2: renamed from eth2
[ 91.180803][ T5940] netdevsim netdevsim0 netdevsim3: renamed from eth3
[ 91.492926][ T5940] 8021q: adding VLAN 0 to HW filter on device bond0
[ 91.548808][ T5940] 8021q: adding VLAN 0 to HW filter on device team0
[ 91.570918][ T1015] bridge0: port 1(bridge_slave_0) entered blocking state
[ 91.578359][ T1015] bridge0: port 1(bridge_slave_0) entered forwarding state
[ 91.638837][ T1015] bridge0: port 2(bridge_slave_1) entered blocking state
[ 91.646007][ T1015] bridge0: port 2(bridge_slave_1) entered forwarding state
[ 91.688028][ T5940] hsr0: Slave B (hsr_slave_1) is not up; please bring it up to get a fully working HSR network
[ 91.861733][ T5940] 8021q: adding VLAN 0 to HW filter on device batadv0
[ 91.913142][ T5940] veth0_vlan: entered promiscuous mode
[ 91.927519][ T5940] veth1_vlan: entered promiscuous mode
[ 91.959185][ T5940] veth0_macvtap: entered promiscuous mode
[ 91.969886][ T5940] veth1_macvtap: entered promiscuous mode
[ 91.988597][ T5940] batman_adv: batadv0: Interface activated: batadv_slave_0
[ 92.003588][ T5940] batman_adv: batadv0: Interface activated: batadv_slave_1
[ 92.018996][ T138] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[ 92.029337][ T138] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[ 92.041299][ T138] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[ 92.052158][ T138] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[ 92.054178][ T5150] Bluetooth: hci0: command tx timeout
[ 92.126119][ T138] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[ 92.140328][ T138] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[ 92.170290][ T1015] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[ 92.178614][ T1015] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)
[ 92.539270][ T49] cfg80211: failed to load regulatory.db


syzkaller build log:
go env (err=<nil>)
AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE='auto'
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/syzkaller/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/syzkaller/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1432137956=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/syzkaller/jobs-2/linux/gopath/src/github.com/google/syzkaller/go.mod'
GOMODCACHE='/syzkaller/jobs-2/linux/gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/syzkaller/jobs-2/linux/gopath'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/syzkaller/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24.4'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at d6526ea3e
nothing to commit, working tree clean


tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
go list -f '{{.Stale}}' -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=d6526ea3e6ad9081c902859bbb80f9f840377cb4 -X github.com/google/syzkaller/prog.gitRevisionDate=20251126-113115" ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=d6526ea3e6ad9081c902859bbb80f9f840377cb4 -X github.com/google/syzkaller/prog.gitRevisionDate=20251126-113115" ./sys/syz-sysgen
make .descriptions
tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
bin/syz-sysgen
touch .descriptions
GOOS=linux GOARCH=amd64 go build -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=d6526ea3e6ad9081c902859bbb80f9f840377cb4 -X github.com/google/syzkaller/prog.gitRevisionDate=20251126-113115" -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
mkdir -p ./bin/linux_amd64
g++ -o ./bin/linux_amd64/syz-executor executor/executor.cc \
-m64 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow -Wno-array-bounds -Wno-format-overflow -Wno-unused-but-set-variable -Wno-unused-command-line-argument -static-pie -std=c++17 -I. -Iexecutor/_include -DGOOS_linux=1 -DGOARCH_amd64=1 \
-DHOSTGOOS_linux=1 -DGIT_REVISION=\"d6526ea3e6ad9081c902859bbb80f9f840377cb4\"
/usr/bin/ld: /tmp/ccDM8VfB.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x104): warning: Using 'gethostbyname' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
./tools/check-syzos.sh 2>/dev/null



Tested on:

commit: 46fe65a2 Add linux-next specific files for 20260116
git tree: linux-next
kernel config: https://syzkaller.appspot.com/x/.config?x=9c0b39f55c418575

dashboard link: https://syzkaller.appspot.com/bug?extid=c27fa543e10a45d4e149
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=10fb33fc580000

[syzbot]

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+c27fa5...@syzkaller.appspotmail.com
Tested-by: syzbot+c27fa5...@syzkaller.appspotmail.com

Tested on:

commit: 46fe65a2 Add linux-next specific files for 20260116
git tree: linux-next

console output: https://syzkaller.appspot.com/x/log.txt?x=12646b9a580000

kernel config: https://syzkaller.appspot.com/x/.config?x=9c0b39f55c418575
dashboard link: https://syzkaller.appspot.com/bug?extid=c27fa543e10a45d4e149
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=102c8b9a580000

Note: testing is done by a robot and is best-effort only.

[Lorenzo Stoakes]

On Sat, Jan 17, 2026 at 11:30:24PM -0800, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: b775e489bec7 Add linux-next specific files for 20260114
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=15dbc444580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2dcf53f0a51185
> dashboard link: https://syzkaller.appspot.com/bug?extid=c27fa543e10a45d4e149
> compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17070522580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1683f99a580000

Thanks, of course being a fault injection thing it's hard to repro :))

Yup this is a nasty additional and impossible-to-hit-in-practice case the
series didn't account for, this time in anon_vma_fork().

Very annoyingly, it violates assumptions made because we try to free up a
partially set up anon_vma.

I'll rework my series + respin to account for this.

Cheers, Lorenzo