CVE-2024-50067: In the Linux kernel, the following vulnerability has been resolved:  uprobe: avoid out-of-bounds memory access of fetching args  Uprobe needs to fetch args into a percpu buffer, and then copy to ring buffer to avoid non-atomic context problem.  Sometimes user-space strings, arrays can be very large, but the size of percpu buffer is only page size. And store_trace_args() won't check whether these data exceeds a single page or not, caused out-of-bounds memory access.  It could be reproduced by following steps: 1. build kernel with CONFIG_KASAN enabled 2. save follow program as test.c  ``` \#include <stdio.h> \#include <stdlib.h> \#include <string.h>  // If string length large than MAX_STRING_SIZE, the fetch_store_strlen() // will return 0, cause __get_data_size() return shorter size, and // store_trace_args() will not trigger out-of-bounds access. // So make string length less than 4096. \#define STRLEN 4093  void generate_string(char *str, int n) {     int i;     for (i = 0; i < n; ++i)     {         char c = i % 26 + 'a';         str[i] = c;     }     str[n-1] = '\0'; }  void print_string(char *str) {     printf("%s\n", str); }  int main() {     char tmp[STRLEN];      generate_string(tmp, STRLEN);     print_string(tmp);      return 0; } ``` 3. compile program `gcc -o test test.c`  4. get the offset of `print_string()` ``` objdump -t test | grep -w print_string 0000000000401199 g     F .text  000000000000001b              print_string ```  5. configure uprobe with offset 0x1199 ``` off=0x1199  cd /sys/kernel/debug/tracing/ echo "p /root/test:${off} arg1=+0(%di):ustring arg2=\$comm arg3=+0(%di):ustring"  > uprobe_events echo 1 > events/uprobes/enable echo 1 > tracing_on ```  6. run `test`, and kasan will report error. ================================================================== BUG: KASAN: use-after-free in strncpy_from_user+0x1d6/0x1f0 Write of size 8 at addr ffff88812311c004 by task test/499CPU: 0 UID: 0 PID: 499 Comm: test Not tainted 6.12.0-rc3+ #18 Hardware name: Red Hat KVM, BIOS 1.16.0-4.al8 04/01/2014 Call Trace:  <TASK>  dump_stack_lvl+0x55/0x70  print_address_description.constprop.0+0x27/0x310  kasan_report+0x10f/0x120  ? strncpy_from_user+0x1d6/0x1f0  strncpy_from_user+0x1d6/0x1f0  ? rmqueue.constprop.0+0x70d/0x2ad0  process_fetch_insn+0xb26/0x1470  ? __pfx_process_fetch_insn+0x10/0x10  ? _raw_spin_lock+0x85/0xe0  ? __pfx__raw_spin_lock+0x10/0x10  ? __pte_offset_map+0x1f/0x2d0  ? unwind_next_frame+0xc5f/0x1f80  ? arch_stack_walk+0x68/0xf0  ? is_bpf_text_address+0x23/0x30  ? kernel_text_address.part.0+0xbb/0xd0  ? __kernel_text_address+0x66/0xb0  ? unwind_get_return_address+0x5e/0xa0  ? __pfx_stack_trace_consume_entry+0x10/0x10  ? arch_stack_walk+0xa2/0xf0  ? _raw_spin_lock_irqsave+0x8b/0xf0  ? __pfx__raw_spin_lock_irqsave+0x10/0x10  ? depot_alloc_stack+0x4c/0x1f0  ? _raw_spin_unlock_irqrestore+0xe/0x30  ? stack_depot_save_flags+0x35d/0x4f0  ? kasan_save_stack+0x34/0x50  ? kasan_save_stack+0x24/0x50  ? mutex_lock+0x91/0xe0  ? __pfx_mutex_lock+0x10/0x10  prepare_uprobe_buffer.part.0+0x2cd/0x500  uprobe_dispatcher+0x2c3/0x6a0  ? __pfx_uprobe_dispatcher+0x10/0x10  ? __kasan_slab_alloc+0x4d/0x90  handler_chain+0xdd/0x3e0  handle_swbp+0x26e/0x3d0  ? __pfx_handle_swbp+0x10/0x10  ? uprobe_pre_sstep_notifier+0x151/0x1b0  irqentry_exit_to_user_mode+0xe2/0x1b0  asm_exc_int3+0x39/0x40 RIP: 0033:0x401199 Code: 01 c2 0f b6 45 fb 88 02 83 45 fc 01 8b 45 fc 3b 45 e4 7c b7 8b 45 e4 48 98 48 8d 50 ff 48 8b 45 e8 48 01 d0 ce RSP: 002b:00007ffdf00576a8 EFLAGS: 00000206 RAX: 00007ffdf00576b0 RBX: 0000000000000000 RCX: 0000000000000ff2 RDX: 0000000000000ffc RSI: 0000000000000ffd RDI: 00007ffdf00576b0 RBP: 00007ffdf00586b0 R08: 00007feb2f9c0d20 R09: 00007feb2f9c0d20 R10: 0000000000000001 R11: 0000000000000202 R12: 0000000000401040 R13: 00007ffdf0058780 R14: 0000000000000000 R15: 0000000000000000  </TASK>  This commit enforces the buffer's maxlen less than a page-size to avoid store_trace_args() out-of-memory access.