Upstream information
Description
In the Linux kernel, the following vulnerability has been resolved:tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().
syzbot reported a weird reqsk->rsk_refcnt underflow in
__inet_csk_reqsk_queue_drop().
The captured reqsk_put() in __inet_csk_reqsk_queue_drop()
is called only when it successfully removes reqsk from ehash.
Moreover, reqsk_timer_handler() calls another reqsk_put()
after that.
This indicates that the reqsk was missing both refcnts for
ehash and the timer itself.
Since all the syzbot reports had PREEMPT_RT enabled, the only
possible scenario is that reqsk_queue_hash_req() is preempted
after mod_timer() and before refcount_set(), and then the timer
triggered after 1s aborts the reqsk due to its listener's close().
Let's wrap mod_timer() and refcount_set() with
preempt_disable_nested() and preempt_enable_nested().
Note that inet_ehash_insert() holds the normal spin_lock()
(mutex in PREEMPT_RT), so it must be called outside of
preempt_disable_nested(), but this is fine.
The lookup path just ignores 0 sk_refcnt entries in ehash
and tries to create another reqsk, but this will fail at
inet_ehash_insert().
[0]:
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16
Modules linked in:
CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f
RSP: 0000:ffffc90000157948 EFLAGS: 00010246
RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00
RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005
R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568
R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0
Call Trace:
<TASK>
__refcount_sub_and_test include/linux/refcount.h:400 [inline]
__refcount_dec_and_test include/linux/refcount.h:432 [inline]
refcount_dec_and_test include/linux/refcount.h:450 [inline]
reqsk_put include/net/request_sock.h:136 [inline]
__inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007
reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403
handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
run_ktimerd+0x69/0x100 kernel/softirq.c:1151
smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
SUSE information
Overall state of this security issue: New
This issue is currently rated as having not set severity.
Note from the SUSE Security Team on the kernel-default package
SUSE will no longer fix all CVEs in the Linux Kernel anymore, but declare some bug classes as won't fix. Please refer to TID 21496 for more details. No SUSE Bugzilla entries cross referenced. No SUSE Security Announcements cross referenced.Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Public Cloud 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Public Cloud 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP7 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 16.0 | kernel-default | Analysis |
| SUSE Linux Enterprise Server 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 16.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP applications 16.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-source | Analysis |
| SUSE Linux Micro 6.0 | kernel-default | Analysis |
| SUSE Linux Micro 6.0 | kernel-source | Analysis |
| SUSE Linux Micro 6.0 | kernel-source-rt | Analysis |
| SUSE Linux Micro 6.1 | kernel-default | Analysis |
| SUSE Linux Micro 6.1 | kernel-source | Analysis |
| SUSE Linux Micro 6.1 | kernel-source-rt | Analysis |
| SUSE Linux Micro 6.2 | kernel-default | Analysis |
| SUSE Linux Micro 6.2 | kernel-source | Analysis |
| SUSE Real Time Module 15 SP7 | kernel-source-rt | Analysis |
| openSUSE Leap 16.0 | kernel-source | Analysis |
| Products under Long Term Service Pack support and receiving important and critical security fixes. | ||
| SUSE Linux Enterprise High Performance Computing 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-default | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP6-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP6-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | Analysis |
| SUSE Manager Proxy 4.3 | kernel-source | Analysis |
| SUSE Manager Proxy LTS 4.3 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.3 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server LTS 4.3 | kernel-source | Analysis |
| SUSE Manager Server 4.3 | kernel-source | Analysis |
| SUSE Manager Server LTS 4.3 | kernel-source | Analysis |
| Products past their end of life and not receiving proactive updates anymore. | ||
| SUSE CaaS Platform 4.0 | kernel-source | Analysis |
| SUSE Enterprise Storage 6 | kernel-source | Analysis |
| SUSE Enterprise Storage 7 | kernel-source | Analysis |
| SUSE Enterprise Storage 7.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 11 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 12 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.0 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.1 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Real Time 15 SP5 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Server 11 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 12 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source | Analysis |
| SUSE Manager Proxy 4.0 | kernel-source | Analysis |
| SUSE Manager Proxy 4.1 | kernel-source | Analysis |
| SUSE Manager Proxy 4.2 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.0 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.1 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.2 | kernel-source | Analysis |
| SUSE Manager Server 4.0 | kernel-source | Analysis |
| SUSE Manager Server 4.1 | kernel-source | Analysis |
| SUSE Manager Server 4.2 | kernel-source | Analysis |
| SUSE OpenStack Cloud 9 | kernel-source | Analysis |
| SUSE OpenStack Cloud Crowbar 9 | kernel-source | Analysis |
| SUSE Real Time Module 15 SP4 | kernel-source-rt | Analysis |
| SUSE Real Time Module 15 SP5 | kernel-source-rt | Analysis |
| openSUSE Leap 15.3 | kernel-source | Analysis |
| openSUSE Leap 15.4 | kernel-source | Analysis |
| openSUSE Leap 15.4 | kernel-source-rt | Analysis |
| openSUSE Leap 15.5 | kernel-source | Analysis |
| openSUSE Leap 15.5 | kernel-source-rt | Analysis |
| openSUSE Leap 15.6 | kernel-source | Analysis |
SUSE Timeline for this CVE
CVE page created: Thu Jun 25 12:12:10 2026CVE page last modified: Thu Jun 25 13:33:01 2026