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For a size-bearing user argument, syscall_copy_user_array() passes the register-supplied pointer directly to __copy_from_user(), which assumes the user address has already been checked. On x86-64 this can copy mapped kernel memory into the raw event. An unprivileged task can open a task-bound sys_enter_write perf event at perf_event_paranoid=2 and disclose that memory with a write() that even fails with EBADF. Use copy_from_user() for each actual array pointer. Use it in the default trace_user_fault_read() path as well: the original syscall-array tracing implementation used that path, and the helper is documented to use copy_from_user(). Keep the existing length limits and per-argument fault handling, so valid user data is recorded as before and failed copies do not contribute bytes to the event. Fixes: b4f7624cfc94 ("tracing: Have system call events record user array data") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-6-astra Signed-off-by: Kyle Zeng --- kernel/trace/trace.c | 2 +- kernel/trace/trace_syscalls.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e4a490d3d08c..07acbc44d99c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6263,7 +6263,7 @@ char *trace_user_fault_read(struct trace_user_buf_info *tinfo, if (copy_func) { ret = copy_func(buffer, ptr, size, data); } else { - ret = __copy_from_user(buffer, ptr, size); + ret = copy_from_user(buffer, ptr, size); } preempt_disable_notrace(); diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index e35744049e3f..d9190fdc030d 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -683,7 +683,7 @@ static int syscall_copy_user_array(char *buf, const char __user *ptr, for (int i = 0; i < args->uargs; i++, buf += SYSCALL_FAULT_ARG_SZ) { ptr = (char __user *)args->ptr_array[i]; - ret = __copy_from_user(buf, ptr, size); + ret = copy_from_user(buf, ptr, size); args->read[i] = ret ? -1 : size; } return 0; -- 2.53.0