There is a critical race condition in kprobe initialization that can lead to
NULL pointer dereference and kernel crash.
[1135630.084782] Unable to handle kernel paging request at virtual address 0000710a04630000
...
[1135630.260314] pstate: 404003c9 (nZcv DAIF +PAN -UAO)
[1135630.269239] pc : kprobe_perf_func+0x30/0x260
[1135630.277643] lr : kprobe_dispatcher+0x44/0x60
[1135630.286041] sp : ffffaeff4977fa40
[1135630.293441] x29: ffffaeff4977fa40 x28: ffffaf015340e400
[1135630.302837] x27: 0000000000000000 x26: 0000000000000000
[1135630.312257] x25: ffffaf029ed108a8 x24: ffffaf015340e528
[1135630.321705] x23: ffffaeff4977fc50 x22: ffffaeff4977fc50
[1135630.331154] x21: 0000000000000000 x20: ffffaeff4977fc50
[1135630.340586] x19: ffffaf015340e400 x18: 0000000000000000
[1135630.349985] x17: 0000000000000000 x16: 0000000000000000
[1135630.359285] x15: 0000000000000000 x14: 0000000000000000
[1135630.368445] x13: 0000000000000000 x12: 0000000000000000
[1135630.377473] x11: 0000000000000000 x10: 0000000000000000
[1135630.386411] x9 : 0000000000000000 x8 : 0000000000000000
[1135630.395252] x7 : 0000000000000000 x6 : 0000000000000000
[1135630.403963] x5 : 0000000000000000 x4 : 0000000000000000
[1135630.412545] x3 : 0000710a04630000 x2 : 0000000000000006
[1135630.421021] x1 : ffffaeff4977fc50 x0 : 0000710a04630000
[1135630.429410] Call trace:
[1135630.434828] kprobe_perf_func+0x30/0x260
[1135630.441661] kprobe_dispatcher+0x44/0x60
[1135630.448396] aggr_pre_handler+0x70/0xc8
[1135630.454959] kprobe_breakpoint_handler+0x140/0x1e0
[1135630.462435] brk_handler+0xbc/0xd8
[1135630.468437] do_debug_exception+0x84/0x138
[1135630.475074] el1_dbg+0x18/0x8c
[1135630.480582] security_file_permission+0x0/0xd0
[1135630.487426] vfs_write+0x70/0x1c0
[1135630.493059] ksys_write+0x5c/0xc8
[1135630.498638] __arm64_sys_write+0x24/0x30
[1135630.504821] el0_svc_common+0x78/0x130
[1135630.510838] el0_svc_handler+0x38/0x78
[1135630.516834] el0_svc+0x8/0x1b0
kernel/trace/trace_kprobe.c: 1308
0xffff3df8995039ec <kprobe_perf_func+0x2c>: ldr x21, [x24,#120]
include/linux/compiler.h: 294
0xffff3df8995039f0 <kprobe_perf_func+0x30>: ldr x1, [x21,x0]
kernel/trace/trace_kprobe.c
1308: head = this_cpu_ptr(call->perf_events);
1309: if (hlist_empty(head))
1310: return 0;
crash> struct trace_event_call -o
struct trace_event_call {
...
[120] struct hlist_head *perf_events; //(call->perf_event)
...
}
crash> struct trace_event_call ffffaf015340e528
struct trace_event_call {
...
perf_events = 0xffff0ad5fa89f088, //this value is correct, but x21 = 0
...
}
Race Condition Analysis:
The race occurs between kprobe activation and perf_events initialization:
CPU0 CPU1
==== ====
perf_kprobe_init
perf_trace_event_init
tp_event->perf_events = list;(1)
tp_event->class->reg (2)← KPROBE ACTIVE
Debug exception triggers
...
kprobe_dispatcher
kprobe_perf_func (tk->tp.flags & TP_FLAG_PROFILE)
head = this_cpu_ptr(call->perf_events)(3)
(perf_events is still NULL)
Problem:
1. CPU0 executes (1) assigning tp_event->perf_events = list
2. CPU0 executes (2) enabling kprobe functionality via class->reg()
3. CPU1 triggers and reaches kprobe_dispatcher
4. CPU1 checks TP_FLAG_PROFILE - condition passes (step 2 completed)
5. CPU1 calls kprobe_perf_func() and crashes at (3) because
call->perf_events is still NULL
CPU1 sees that kprobe functionality is enabled but does not see that
perf_events has been assigned.
Add pairing read and write memory barriers to guarantee that if CPU1
sees that kprobe functionality is enabled, it must also see that
perf_events has been assigned.
Link: https://lore.kernel.org/all/20251001022025.44626-1-chenyuan_fl@163.com/
Fixes: 50d780560785 ("tracing/kprobes: Add probe handler dispatcher to support perf and ftrace concurrent use")
Cc: stable@vger.kernel.org
Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
A crash was observed with the following output:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 2899 Comm: syz.2.399 Not tainted 6.17.0-rc5+ #5 PREEMPT(none)
RIP: 0010:trace_kprobe_create_internal+0x3fc/0x1440 kernel/trace/trace_kprobe.c:911
Call Trace:
<TASK>
trace_kprobe_create_cb+0xa2/0xf0 kernel/trace/trace_kprobe.c:1089
trace_probe_create+0xf1/0x110 kernel/trace/trace_probe.c:2246
dyn_event_create+0x45/0x70 kernel/trace/trace_dynevent.c:128
create_or_delete_trace_kprobe+0x5e/0xc0 kernel/trace/trace_kprobe.c:1107
trace_parse_run_command+0x1a5/0x330 kernel/trace/trace.c:10785
vfs_write+0x2b6/0xd00 fs/read_write.c:684
ksys_write+0x129/0x240 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x5d/0x2d0 arch/x86/entry/syscall_64.c:94
</TASK>
Function kmemdup() may return NULL in trace_kprobe_create_internal(), add
check for it's return value.
Link: https://lore.kernel.org/all/20250916075816.3181175-1-wangliang74@huawei.com/
Fixes: 33b4e38baa03 ("tracing: kprobe-event: Allocate string buffers from heap")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Allocate temporary string buffers for parsing kprobe-events from heap instead of stack. Link: https://lore.kernel.org/all/175323427627.57270.5105357260879695051.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Instead of allocating traceprobe_parse_context on stack, allocate it dynamically from heap (slab). This change is likely intended to prevent potential stack overflow issues, which can be a concern in the kernel environment where stack space is limited. Link: https://lore.kernel.org/all/175323425650.57270.280750740753792504.stgit@devnote2/ Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202506240416.nZIhDXoO-lkp@intel.com/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Sort the #include directives in trace_probe* files alphabetically for easier maintenance and avoid double includes. This also groups headers as linux-generic, asm-generic, and local headers. Link: https://lore.kernel.org/all/175323424678.57270.11975372127870059007.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Since the shared trace_probe_log variable can be accessed and
modified via probe event create operation of kprobe_events,
uprobe_events, and dynamic_events, it should be protected.
In the dynamic_events, all operations are serialized by
`dyn_event_ops_mutex`. But kprobe_events and uprobe_events
interfaces are not serialized.
To solve this issue, introduces dyn_event_create(), which runs
create() operation under the mutex, for kprobe_events and
uprobe_events. This also uses lockdep to check the mutex is
held when using trace_probe_log* APIs.
Link: https://lore.kernel.org/all/174684868120.551552.3068655787654268804.stgit@devnote2/
Reported-by: Paul Cacheux <paulcacheux@gmail.com>
Closes: https://lore.kernel.org/all/20250510074456.805a16872b591e2971a4d221@kernel.org/
Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe events")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Pull modules updates from Petr Pavlu: - Use RCU instead of RCU-sched The mix of rcu_read_lock(), rcu_read_lock_sched() and preempt_disable() in the module code and its users has been replaced with just rcu_read_lock() - The rest of changes are smaller fixes and updates * tag 'modules-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux: (32 commits) MAINTAINERS: Update the MODULE SUPPORT section module: Remove unnecessary size argument when calling strscpy() module: Replace deprecated strncpy() with strscpy() params: Annotate struct module_param_attrs with __counted_by() bug: Use RCU instead RCU-sched to protect module_bug_list. static_call: Use RCU in all users of __module_text_address(). kprobes: Use RCU in all users of __module_text_address(). bpf: Use RCU in all users of __module_text_address(). jump_label: Use RCU in all users of __module_text_address(). jump_label: Use RCU in all users of __module_address(). x86: Use RCU in all users of __module_address(). cfi: Use RCU while invoking __module_address(). powerpc/ftrace: Use RCU in all users of __module_text_address(). LoongArch: ftrace: Use RCU in all users of __module_text_address(). LoongArch/orc: Use RCU in all users of __module_address(). arm64: module: Use RCU in all users of __module_text_address(). ARM: module: Use RCU in all users of __module_text_address(). module: Use RCU in all users of __module_text_address(). module: Use RCU in all users of __module_address(). module: Use RCU in search_module_extables(). ...
Add error message when the number of arguments exceeds the limitation. Link: https://lore.kernel.org/all/174055075075.4079315.10916648136898316476.stgit@mhiramat.tok.corp.google.com/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The modules list and module::kallsyms can be accessed under RCU assumption. Remove module_assert_mutex_or_preempt() from find_module_all() so it can be used under RCU protection without warnings. Update its callers to use RCU protection instead of preempt_disable(). Cc: Jiri Kosina <jikos@kernel.org> Cc: Joe Lawrence <joe.lawrence@redhat.com> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: linux-trace-kernel@vger.kernel.org Cc: live-patching@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20250108090457.512198-7-bigeasy@linutronix.de Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Simplify __trace_kprobe_create() by removing gotos. Link: https://lore.kernel.org/all/173643301102.1514810.6149004416601259466.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>