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Thu, 05 Nov 2026 03:33:50 -0800 (PST) Date: Thu, 05 Nov 2026 03:33:50 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6aec699e.73adde43.12e2c1.0000.GAE@google.com> Subject: [syzbot] [kernel?] general protection fault in psi_task_change From: syzbot To: anna-maria@linutronix.de, frederic@kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tglx@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 05441d697f7f Merge tag 'cocci-7.4-rc1' of git://git.kernel.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1007668d580000 kernel config: https://syzkaller.appspot.com/x/.config?x=1cf189394a856f11 dashboard link: https://syzkaller.appspot.com/bug?extid=66e09ade4298957334df compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1422d381580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1407668d580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-05441d69.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/0edd3964be19/vmlinux-05441d69.xz kernel image: https://storage.googleapis.com/syzbot-assets/84d6d8dd5648/bzImage-05441d69.xz AI-generated root cause summary: In drivers/pci/proc.c, proc_bus_pci_write() allows writing directly to the PCI configuration space of PCI devices including the host bridge (device 00:00.0). Writing arbitrary data to host bridge configuration registers reconfigures physical memory routing registers (such as PCIEXBAR, PAM, and TOLUD), causing physical RAM regions backing kernel allocations (such as struct css_set) to become unmapped and return all-ones (0xff). When the scheduler invokes psi_task_change() -> task_psi_group() -> cgroup_psi(), reading cset->dfl_cgrp from the affected memory yields 0xffffffffffffffff (-1), causing cgroup_ino() to access an invalid offset that triggers a general protection fault and kernel panic. full analysis: https://syzkaller.appspot.com/x/ai_root_cause?x=66e09ade4298957334df IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+66e09ade4298957334df@syzkaller.appspotmail.com Oops: general protection fault, probably for non-canonical address 0xdffffc0000000033: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000198-0x000000000000019f] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:cgroup_ino include/linux/cgroup.h:724 [inline] RIP: 0010:cgroup_psi include/linux/psi.h:39 [inline] RIP: 0010:task_psi_group kernel/sched/psi.c:884 [inline] RIP: 0010:task_psi_group kernel/sched/psi.c:880 [inline] RIP: 0010:psi_task_change+0x20f/0x530 kernel/sched/psi.c:916 Code: 03 80 3c 02 00 0f 85 ff 02 00 00 4d 8b bd 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bf a0 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 02 00 00 4d 8b af a0 01 00 00 48 ba 00 00 00 RSP: 0018:ffffc900006a0c68 EFLAGS: 00010007 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000033 RSI: ffffffff8e60120c RDI: 000000000000019f RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff888054570000 R14: 0000000000000001 R15: ffffffffffffffff FS: 0000000000000000(0000) GS:ffff8880d457c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5894989140 CR3: 00000000372ab000 CR4: 0000000000352ef0 Call Trace: psi_enqueue kernel/sched/stats.h:159 [inline] enqueue_task+0x1dc/0x4f0 kernel/sched/core.c:2199 activate_task kernel/sched/core.c:2237 [inline] ttwu_do_activate+0x174/0x800 kernel/sched/core.c:3897 ttwu_queue kernel/sched/core.c:4150 [inline] try_to_wake_up+0xce0/0x1ca0 kernel/sched/core.c:4488 hrtimer_wakeup+0x47/0x60 kernel/time/hrtimer.c:2335 __run_hrtimer kernel/time/hrtimer.c:2079 [inline] __hrtimer_run_queues+0x448/0x9a0 kernel/time/hrtimer.c:2136 hrtimer_interrupt+0x441/0xaa0 kernel/time/hrtimer.c:2255 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: 67 a1 02 e9 43 61 03 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d c3 7d 1d 00 fb f4 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc90000177e00 EFLAGS: 00000206 RAX: 000000000003cdf9 RBX: ffff88802069a580 RCX: ffffffff8bee4325 RDX: 0000000000000001 RSI: ffffffff8e628221 RDI: ffffffff8c835380 RBP: ffffed10040d34b0 R08: 0000000000000001 R09: ffffed100d426825 R10: ffff88806a13412b R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 1ffff9200002efc4 R15: dffffc0000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline] default_idle+0x9/0x10 arch/x86/kernel/process.c:768 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x3ae/0x5b0 kernel/sched/idle.c:355 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:458 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x158 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:cgroup_ino include/linux/cgroup.h:724 [inline] RIP: 0010:cgroup_psi include/linux/psi.h:39 [inline] RIP: 0010:task_psi_group kernel/sched/psi.c:884 [inline] RIP: 0010:task_psi_group kernel/sched/psi.c:880 [inline] RIP: 0010:psi_task_change+0x20f/0x530 kernel/sched/psi.c:916 Code: 03 80 3c 02 00 0f 85 ff 02 00 00 4d 8b bd 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bf a0 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 02 00 00 4d 8b af a0 01 00 00 48 ba 00 00 00 RSP: 0018:ffffc900006a0c68 EFLAGS: 00010007 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000033 RSI: ffffffff8e60120c RDI: 000000000000019f RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff888054570000 R14: 0000000000000001 R15: ffffffffffffffff FS: 0000000000000000(0000) GS:ffff8880d457c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5894989140 CR3: 00000000372ab000 CR4: 0000000000352ef0 ---------------- Code disassembly (best guess): 0: 03 80 3c 02 00 0f add 0xf00023c(%rax),%eax 6: 85 ff test %edi,%edi 8: 02 00 add (%rax),%al a: 00 4d 8b add %cl,-0x75(%rbp) d: bd 88 00 00 00 mov $0x88,%ebp 12: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 19: fc ff df 1c: 49 8d bf a0 01 00 00 lea 0x1a0(%r15),%rdi 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 0f 85 e0 02 00 00 jne 0x314 34: 4d 8b af a0 01 00 00 mov 0x1a0(%r15),%r13 3b: 48 rex.W 3c: ba .byte 0xba 3d: 00 00 add %al,(%rax) --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup