From a2501032de0d1bc7971b2e43c03da534ac10ee9b Mon Sep 17 00:00:00 2001 From: Wang Liang Date: Tue, 16 Sep 2025 14:39:48 +0800 Subject: [PATCH 1/3] tracing/osnoise: Fix slab-out-of-bounds in _parse_integer_limit() When config osnoise cpus by write() syscall, the following KASAN splat may be observed: BUG: KASAN: slab-out-of-bounds in _parse_integer_limit+0x103/0x130 Read of size 1 at addr ffff88810121e3a1 by task test/447 CPU: 1 UID: 0 PID: 447 Comm: test Not tainted 6.17.0-rc6-dirty #288 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: dump_stack_lvl+0x55/0x70 print_report+0xcb/0x610 kasan_report+0xb8/0xf0 _parse_integer_limit+0x103/0x130 bitmap_parselist+0x16d/0x6f0 osnoise_cpus_write+0x116/0x2d0 vfs_write+0x21e/0xcc0 ksys_write+0xee/0x1c0 do_syscall_64+0xa8/0x2a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f This issue can be reproduced by below code: const char *cpulist = "1"; int fd=open("/sys/kernel/debug/tracing/osnoise/cpus", O_WRONLY); write(fd, cpulist, strlen(cpulist)); Function bitmap_parselist() was called to parse cpulist, it require that the parameter 'buf' must be terminated with a '\0' or '\n'. Fix this issue by adding a '\0' to 'buf' in osnoise_cpus_write(). Cc: Cc: Cc: Link: https://lore.kernel.org/20250916063948.3154627-1-wangliang74@huawei.com Fixes: 17f89102fe23 ("tracing/osnoise: Allow arbitrarily long CPU string") Signed-off-by: Wang Liang Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_osnoise.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 337bc0eb5d71..dc734867f0fc 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2325,12 +2325,13 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count, if (count < 1) return 0; - buf = kmalloc(count, GFP_KERNEL); + buf = kmalloc(count + 1, GFP_KERNEL); if (!buf) return -ENOMEM; if (copy_from_user(buf, ubuf, count)) return -EFAULT; + buf[count] = '\0'; if (!zalloc_cpumask_var(&osnoise_cpumask_new, GFP_KERNEL)) return -ENOMEM; From 1da3f145ede481607a93472d2a1f597d6e998eb4 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Fri, 19 Sep 2025 10:15:56 +0900 Subject: [PATCH 2/3] tracing: dynevent: Add a missing lockdown check on dynevent Since dynamic_events interface on tracefs is compatible with kprobe_events and uprobe_events, it should also check the lockdown status and reject if it is set. Cc: Mathieu Desnoyers Link: https://lore.kernel.org/175824455687.45175.3734166065458520748.stgit@devnote2 Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_dynevent.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c index 5d64a18cacac..d06854bd32b3 100644 --- a/kernel/trace/trace_dynevent.c +++ b/kernel/trace/trace_dynevent.c @@ -230,6 +230,10 @@ static int dyn_event_open(struct inode *inode, struct file *file) { int ret; + ret = security_locked_down(LOCKDOWN_TRACEFS); + if (ret) + return ret; + ret = tracing_check_open_get_tr(NULL); if (ret) return ret; From 0db0934e7f9bb624ed98a665890dbe249f65b8fd Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 22 Sep 2025 15:35:22 +0900 Subject: [PATCH 3/3] tracing: fgraph: Protect return handler from recursion loop function_graph_enter_regs() prevents itself from recursion by ftrace_test_recursion_trylock(), but __ftrace_return_to_handler(), which is called at the exit, does not prevent such recursion. Therefore, while it can prevent recursive calls from fgraph_ops::entryfunc(), it is not able to prevent recursive calls to fgraph from fgraph_ops::retfunc(), resulting in a recursive loop. This can lead an unexpected recursion bug reported by Menglong. is_endbr() is called in __ftrace_return_to_handler -> fprobe_return -> kprobe_multi_link_exit_handler -> is_endbr. To fix this issue, acquire ftrace_test_recursion_trylock() in the __ftrace_return_to_handler() after unwind the shadow stack to mark this section must prevent recursive call of fgraph inside user-defined fgraph_ops::retfunc(). This is essentially a fix to commit 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer"), because before that fgraph was only used from the function graph tracer. Fprobe allowed user to run any callbacks from fgraph after that commit. Reported-by: Menglong Dong Closes: https://lore.kernel.org/all/20250918120939.1706585-1-dongml2@chinatelecom.cn/ Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Cc: stable@vger.kernel.org Cc: Peter Zijlstra Link: https://lore.kernel.org/175852292275.307379.9040117316112640553.stgit@devnote2 Signed-off-by: Masami Hiramatsu (Google) Acked-by: Jiri Olsa Tested-by: Menglong Dong Acked-by: Menglong Dong Signed-off-by: Steven Rostedt (Google) --- kernel/trace/fgraph.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 1e3b32b1e82c..484ad7a18463 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -815,6 +815,7 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointe unsigned long bitmap; unsigned long ret; int offset; + int bit; int i; ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer, &offset); @@ -829,6 +830,15 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointe if (fregs) ftrace_regs_set_instruction_pointer(fregs, ret); + bit = ftrace_test_recursion_trylock(trace.func, ret); + /* + * This can fail because ftrace_test_recursion_trylock() allows one nest + * call. If we are already in a nested call, then we don't probe this and + * just return the original return address. + */ + if (unlikely(bit < 0)) + goto out; + #ifdef CONFIG_FUNCTION_GRAPH_RETVAL trace.retval = ftrace_regs_get_return_value(fregs); #endif @@ -852,6 +862,8 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointe } } + ftrace_test_recursion_unlock(bit); +out: /* * The ftrace_graph_return() may still access the current * ret_stack structure, we need to make sure the update of