{"id":"CVE-2026-45957","summary":"rcu: Fix rcu_read_unlock() deadloop due to softirq","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nrcu: Fix rcu_read_unlock() deadloop due to softirq\n\nCommit 5f5fa7ea89dc (\"rcu: Don't use negative nesting depth in\n__rcu_read_unlock()\") removes the recursion-protection code from\n__rcu_read_unlock(). Therefore, we could invoke the deadloop in\nraise_softirq_irqoff() with ftrace enabled as follows:\n\nWARNING: CPU: 0 PID: 0 at kernel/trace/trace.c:3021 __ftrace_trace_stack.constprop.0+0x172/0x180\nModules linked in: my_irq_work(O)\nCPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G O 6.18.0-rc7-dirty #23 PREEMPT(full)\nTainted: [O]=OOT_MODULE\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014\nRIP: 0010:__ftrace_trace_stack.constprop.0+0x172/0x180\nRSP: 0018:ffffc900000034a8 EFLAGS: 00010002\nRAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000\nRDX: 0000000000000003 RSI: ffffffff826d7b87 RDI: ffffffff826e9329\nRBP: 0000000000090009 R08: 0000000000000005 R09: ffffffff82afbc4c\nR10: 0000000000000008 R11: 0000000000011d7a R12: 0000000000000000\nR13: ffff888003874100 R14: 0000000000000003 R15: ffff8880038c1054\nFS:  0000000000000000(0000) GS:ffff8880fa8ea000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 000055b31fa7f540 CR3: 00000000078f4005 CR4: 0000000000770ef0\nPKRU: 55555554\nCall Trace:\n \u003cIRQ\u003e\n trace_buffer_unlock_commit_regs+0x6d/0x220\n trace_event_buffer_commit+0x5c/0x260\n trace_event_raw_event_softirq+0x47/0x80\n raise_softirq_irqoff+0x6e/0xa0\n rcu_read_unlock_special+0xb1/0x160\n unwind_next_frame+0x203/0x9b0\n __unwind_start+0x15d/0x1c0\n arch_stack_walk+0x62/0xf0\n stack_trace_save+0x48/0x70\n __ftrace_trace_stack.constprop.0+0x144/0x180\n trace_buffer_unlock_commit_regs+0x6d/0x220\n trace_event_buffer_commit+0x5c/0x260\n trace_event_raw_event_softirq+0x47/0x80\n raise_softirq_irqoff+0x6e/0xa0\n rcu_read_unlock_special+0xb1/0x160\n unwind_next_frame+0x203/0x9b0\n __unwind_start+0x15d/0x1c0\n arch_stack_walk+0x62/0xf0\n stack_trace_save+0x48/0x70\n __ftrace_trace_stack.constprop.0+0x144/0x180\n trace_buffer_unlock_commit_regs+0x6d/0x220\n trace_event_buffer_commit+0x5c/0x260\n trace_event_raw_event_softirq+0x47/0x80\n raise_softirq_irqoff+0x6e/0xa0\n rcu_read_unlock_special+0xb1/0x160\n unwind_next_frame+0x203/0x9b0\n __unwind_start+0x15d/0x1c0\n arch_stack_walk+0x62/0xf0\n stack_trace_save+0x48/0x70\n __ftrace_trace_stack.constprop.0+0x144/0x180\n trace_buffer_unlock_commit_regs+0x6d/0x220\n trace_event_buffer_commit+0x5c/0x260\n trace_event_raw_event_softirq+0x47/0x80\n raise_softirq_irqoff+0x6e/0xa0\n rcu_read_unlock_special+0xb1/0x160\n __is_insn_slot_addr+0x54/0x70\n kernel_text_address+0x48/0xc0\n __kernel_text_address+0xd/0x40\n unwind_get_return_address+0x1e/0x40\n arch_stack_walk+0x9c/0xf0\n stack_trace_save+0x48/0x70\n __ftrace_trace_stack.constprop.0+0x144/0x180\n trace_buffer_unlock_commit_regs+0x6d/0x220\n trace_event_buffer_commit+0x5c/0x260\n trace_event_raw_event_softirq+0x47/0x80\n __raise_softirq_irqoff+0x61/0x80\n __flush_smp_call_function_queue+0x115/0x420\n __sysvec_call_function_single+0x17/0xb0\n sysvec_call_function_single+0x8c/0xc0\n \u003c/IRQ\u003e\n\nCommit b41642c87716 (\"rcu: Fix rcu_read_unlock() deadloop due to IRQ work\")\nfixed the infinite loop in rcu_read_unlock_special() for IRQ work by\nsetting a flag before calling irq_work_queue_on(). We fix this issue by\nsetting the same flag before calling raise_softirq_irqoff() and rename the\nflag to defer_qs_pending for more common.","modified":"2026-06-18T03:54:30.086497086Z","published":"2026-05-27T12:18:13.145Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45957.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1f16679a5aa60238466ce339c35f5e82ece60337"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4a4a6e12c9c829be3f74b7206fa8640fc4e1c566"},{"type":"WEB","url":"https://git.kernel.org/stable/c/979c708e6c9d7fc461daef2dad8b45f22e23464c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c2932e16d8c354404b17123e64daa8e33191e145"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d41e37f26b3157b3f1d10223863519a943aa239b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45957.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45957"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce"},{"fixed":"979c708e6c9d7fc461daef2dad8b45f22e23464c"},{"fixed":"1f16679a5aa60238466ce339c35f5e82ece60337"},{"fixed":"4a4a6e12c9c829be3f74b7206fa8640fc4e1c566"},{"fixed":"c2932e16d8c354404b17123e64daa8e33191e145"},{"fixed":"d41e37f26b3157b3f1d10223863519a943aa239b"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-45957.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.8.0"},{"fixed":"6.6.128"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.75"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-45957.json"}}],"schema_version":"1.7.5"}