This is a note to let you know that I've just added the patch titled kprobes: don't call disarm_kprobe() for disabled kprobes to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kprobes-don-t-call-disarm_kprobe-for-disabled-kprobes.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 9c80e79906b4ca440d09e7f116609262bb747909 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Date: Fri, 12 Aug 2022 19:05:09 -0700 Subject: kprobes: don't call disarm_kprobe() for disabled kprobes From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> commit 9c80e79906b4ca440d09e7f116609262bb747909 upstream. The assumption in __disable_kprobe() is wrong, and it could try to disarm an already disarmed kprobe and fire the WARN_ONCE() below. [0] We can easily reproduce this issue. 1. Write 0 to /sys/kernel/debug/kprobes/enabled. # echo 0 > /sys/kernel/debug/kprobes/enabled 2. Run execsnoop. At this time, one kprobe is disabled. # /usr/share/bcc/tools/execsnoop & [1] 2460 PCOMM PID PPID RET ARGS # cat /sys/kernel/debug/kprobes/list ffffffff91345650 r __x64_sys_execve+0x0 [FTRACE] ffffffff91345650 k __x64_sys_execve+0x0 [DISABLED][FTRACE] 3. Write 1 to /sys/kernel/debug/kprobes/enabled, which changes kprobes_all_disarmed to false but does not arm the disabled kprobe. # echo 1 > /sys/kernel/debug/kprobes/enabled # cat /sys/kernel/debug/kprobes/list ffffffff91345650 r __x64_sys_execve+0x0 [FTRACE] ffffffff91345650 k __x64_sys_execve+0x0 [DISABLED][FTRACE] 4. Kill execsnoop, when __disable_kprobe() calls disarm_kprobe() for the disabled kprobe and hits the WARN_ONCE() in __disarm_kprobe_ftrace(). # fg /usr/share/bcc/tools/execsnoop ^C Actually, WARN_ONCE() is fired twice, and __unregister_kprobe_top() misses some cleanups and leaves the aggregated kprobe in the hash table. Then, __unregister_trace_kprobe() initialises tk->rp.kp.list and creates an infinite loop like this. aggregated kprobe.list -> kprobe.list -. ^ | '.__.' In this situation, these commands fall into the infinite loop and result in RCU stall or soft lockup. cat /sys/kernel/debug/kprobes/list : show_kprobe_addr() enters into the infinite loop with RCU. /usr/share/bcc/tools/execsnoop : warn_kprobe_rereg() holds kprobe_mutex, and __get_valid_kprobe() is stuck in the loop. To avoid the issue, make sure we don't call disarm_kprobe() for disabled kprobes. [0] Failed to disarm kprobe-ftrace at __x64_sys_execve+0x0/0x40 (error -2) WARNING: CPU: 6 PID: 2460 at kernel/kprobes.c:1130 __disarm_kprobe_ftrace.isra.19 (kernel/kprobes.c:1129) Modules linked in: ena CPU: 6 PID: 2460 Comm: execsnoop Not tainted 5.19.0+ #28 Hardware name: Amazon EC2 c5.2xlarge/, BIOS 1.0 10/16/2017 RIP: 0010:__disarm_kprobe_ftrace.isra.19 (kernel/kprobes.c:1129) Code: 24 8b 02 eb c1 80 3d c4 83 f2 01 00 75 d4 48 8b 75 00 89 c2 48 c7 c7 90 fa 0f 92 89 04 24 c6 05 ab 83 01 e8 e4 94 f0 ff <0f> 0b 8b 04 24 eb b1 89 c6 48 c7 c7 60 fa 0f 92 89 04 24 e8 cc 94 RSP: 0018:ffff9e6ec154bd98 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffffffff930f7b00 RCX: 0000000000000001 RDX: 0000000080000001 RSI: ffffffff921461c5 RDI: 00000000ffffffff RBP: ffff89c504286da8 R08: 0000000000000000 R09: c0000000fffeffff R10: 0000000000000000 R11: ffff9e6ec154bc28 R12: ffff89c502394e40 R13: ffff89c502394c00 R14: ffff9e6ec154bc00 R15: 0000000000000000 FS: 00007fe800398740(0000) GS:ffff89c812d80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c00057f010 CR3: 0000000103b54006 CR4: 00000000007706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> __disable_kprobe (kernel/kprobes.c:1716) disable_kprobe (kernel/kprobes.c:2392) __disable_trace_kprobe (kernel/trace/trace_kprobe.c:340) disable_trace_kprobe (kernel/trace/trace_kprobe.c:429) perf_trace_event_unreg.isra.2 (./include/linux/tracepoint.h:93 kernel/trace/trace_event_perf.c:168) perf_kprobe_destroy (kernel/trace/trace_event_perf.c:295) _free_event (kernel/events/core.c:4971) perf_event_release_kernel (kernel/events/core.c:5176) perf_release (kernel/events/core.c:5186) __fput (fs/file_table.c:321) task_work_run (./include/linux/sched.h:2056 (discriminator 1) kernel/task_work.c:179 (discriminator 1)) exit_to_user_mode_prepare (./include/linux/resume_user_mode.h:49 kernel/entry/common.c:169 kernel/entry/common.c:201) syscall_exit_to_user_mode (./arch/x86/include/asm/jump_label.h:55 ./arch/x86/include/asm/nospec-branch.h:384 ./arch/x86/include/asm/entry-common.h:94 kernel/entry/common.c:133 kernel/entry/common.c:296) do_syscall_64 (arch/x86/entry/common.c:87) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) RIP: 0033:0x7fe7ff210654 Code: 15 79 89 20 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb be 0f 1f 00 8b 05 9a cd 20 00 48 63 ff 85 c0 75 11 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 3a f3 c3 48 83 ec 18 48 89 7c 24 08 e8 34 fc RSP: 002b:00007ffdbd1d3538 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000008 RCX: 00007fe7ff210654 RDX: 0000000000000000 RSI: 0000000000002401 RDI: 0000000000000008 RBP: 0000000000000000 R08: 94ae31d6fda838a4 R0900007fe8001c9d30 R10: 00007ffdbd1d34b0 R11: 0000000000000246 R12: 00007ffdbd1d3600 R13: 0000000000000000 R14: fffffffffffffffc R15: 00007ffdbd1d3560 </TASK> Link: https://lkml.kernel.org/r/20220813020509.90805-1-kuniyu@xxxxxxxxxx Fixes: 69d54b916d83 ("kprobes: makes kprobes/enabled works correctly for optimized kprobes.") Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Reported-by: Ayushman Dutta <ayudutta@xxxxxxxxxx> Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Wang Nan <wangnan0@xxxxxxxxxx> Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Cc: Kuniyuki Iwashima <kuni1840@xxxxxxxxx> Cc: Ayushman Dutta <ayudutta@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/kprobes.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1687,12 +1687,14 @@ static struct kprobe *__disable_kprobe(s /* Try to disarm and disable this/parent probe */ if (p == orig_p || aggr_kprobe_disabled(orig_p)) { /* - * If kprobes_all_disarmed is set, orig_p - * should have already been disarmed, so - * skip unneed disarming process. + * Don't be lazy here. Even if 'kprobes_all_disarmed' + * is false, 'orig_p' might not have been armed yet. + * Note arm_all_kprobes() __tries__ to arm all kprobes + * on the best effort basis. */ - if (!kprobes_all_disarmed) + if (!kprobes_all_disarmed && !kprobe_disabled(orig_p)) disarm_kprobe(orig_p, true); + orig_p->flags |= KPROBE_FLAG_DISABLED; } } Patches currently in stable-queue which might be from kuniyu@xxxxxxxxxx are queue-4.14/kprobes-don-t-call-disarm_kprobe-for-disabled-kprobes.patch queue-4.14/net-fix-data-races-around-weight_p-and-dev_weight_-r.patch queue-4.14/ratelimit-fix-data-races-in-___ratelimit.patch queue-4.14/net-fix-a-data-race-around-netdev_budget_usecs.patch queue-4.14/net-fix-a-data-race-around-sysctl_somaxconn.patch queue-4.14/net-fix-a-data-race-around-sysctl_net_busy_read.patch queue-4.14/net-fix-a-data-race-around-netdev_budget.patch queue-4.14/net-fix-a-data-race-around-sysctl_tstamp_allow_data.patch queue-4.14/net-fix-a-data-race-around-sysctl_net_busy_poll.patch