Linux Kernel up to 6.6.127/6.12.74/6.18.13/6.19.3 kernel/trace/trace.c rcu_read_unlock infinite loop

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.6.127/6.12.74/6.18.13/6.19.3. This vulnerability affects the function rcu_read_unlock of the file kernel/trace/trace.c. Such manipulation leads to infinite loop. This vulnerability is uniquely identified as CVE-2026-45957. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.127/6.12.74/6.18.13/6.19.3. It has been rated as critical. Affected by this issue is the function rcu_read_unlock of the file kernel/trace/trace.c. The manipulation with an unknown input leads to a infinite loop vulnerability. Using CWE to declare the problem leads to CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: rcu: Fix rcu_read_unlock() deadloop due to softirq Commit 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in __rcu_read_unlock()") removes the recursion-protection code from __rcu_read_unlock(). Therefore, we could invoke the deadloop in raise_softirq_irqoff() with ftrace enabled as follows: WARNING: CPU: 0 PID: 0 at kernel/trace/trace.c:3021 __ftrace_trace_stack.constprop.0+0x172/0x180 Modules linked in: my_irq_work(O) CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G O 6.18.0-rc7-dirty #23 PREEMPT(full) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:__ftrace_trace_stack.constprop.0+0x172/0x180 RSP: 0018:ffffc900000034a8 EFLAGS: 00010002 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 RDX: 0000000000000003 RSI: ffffffff826d7b87 RDI: ffffffff826e9329 RBP: 0000000000090009 R08: 0000000000000005 R09: ffffffff82afbc4c R10: 0000000000000008 R11: 0000000000011d7a R12: 0000000000000000 R13: ffff888003874100 R14: 0000000000000003 R15: ffff8880038c1054 FS: 0000000000000000(0000) GS:ffff8880fa8ea000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055b31fa7f540 CR3: 00000000078f4005 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: <IRQ> trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 unwind_next_frame+0x203/0x9b0 __unwind_start+0x15d/0x1c0 arch_stack_walk+0x62/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 unwind_next_frame+0x203/0x9b0 __unwind_start+0x15d/0x1c0 arch_stack_walk+0x62/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 unwind_next_frame+0x203/0x9b0 __unwind_start+0x15d/0x1c0 arch_stack_walk+0x62/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 raise_softirq_irqoff+0x6e/0xa0 rcu_read_unlock_special+0xb1/0x160 __is_insn_slot_addr+0x54/0x70 kernel_text_address+0x48/0xc0 __kernel_text_address+0xd/0x40 unwind_get_return_address+0x1e/0x40 arch_stack_walk+0x9c/0xf0 stack_trace_save+0x48/0x70 __ftrace_trace_stack.constprop.0+0x144/0x180 trace_buffer_unlock_commit_regs+0x6d/0x220 trace_event_buffer_commit+0x5c/0x260 trace_event_raw_event_softirq+0x47/0x80 __raise_softirq_irqoff+0x61/0x80 __flush_smp_call_function_queue+0x115/0x420 __sysvec_call_function_single+0x17/0xb0 sysvec_call_function_single+0x8c/0xc0 </IRQ> Commit b41642c87716 ("rcu: Fix rcu_read_unlock() deadloop due to IRQ work") fixed the infinite loop in rcu_read_unlock_special() for IRQ work by setting a flag before calling irq_work_queue_on(). We fix this issue by setting the same flag before calling raise_softirq_irqoff() and rename the flag to defer_qs_pending for more common.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-45957 since 05/13/2026. The exploitation is known to be difficult. Technical details are known, but there is no available exploit.

Upgrading to version 6.6.128, 6.12.75, 6.18.14 or 6.19.4 eliminates this vulnerability. Applying the patch 979c708e6c9d7fc461daef2dad8b45f22e23464c/1f16679a5aa60238466ce339c35f5e82ece60337/4a4a6e12c9c829be3f74b7206fa8640fc4e1c566/c2932e16d8c354404b17123e64daa8e33191e145/d41e37f26b3157b3f1d10223863519a943aa239b is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.127
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
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• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
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• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.12.54
• 6.12.55
• 6.12.56
• 6.12.57
• 6.12.58
• 6.12.59
• 6.12.60
• 6.12.61
• 6.12.62
• 6.12.63
• 6.12.64
• 6.12.65
• 6.12.66
• 6.12.67
• 6.12.68
• 6.12.69
• 6.12.70
• 6.12.71
• 6.12.72
• 6.12.73
• 6.12.74
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Threat Intelligenceinfo

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Entryinfo

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