CVE-2024-50067

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> uprobe: avoid out-of-bounds memory access of fetching args<br /> <br /> Uprobe needs to fetch args into a percpu buffer, and then copy to ring<br /> buffer to avoid non-atomic context problem.<br /> <br /> Sometimes user-space strings, arrays can be very large, but the size of<br /> percpu buffer is only page size. And store_trace_args() won&amp;#39;t check<br /> whether these data exceeds a single page or not, caused out-of-bounds<br /> memory access.<br /> <br /> It could be reproduced by following steps:<br /> 1. build kernel with CONFIG_KASAN enabled<br /> 2. save follow program as test.c<br /> <br /> ```<br /> \#include <br /> \#include <br /> \#include <br /> <br /> // If string length large than MAX_STRING_SIZE, the fetch_store_strlen()<br /> // will return 0, cause __get_data_size() return shorter size, and<br /> // store_trace_args() will not trigger out-of-bounds access.<br /> // So make string length less than 4096.<br /> \#define STRLEN 4093<br /> <br /> void generate_string(char *str, int n)<br /> {<br /> int i;<br /> for (i = 0; i uprobe_events<br /> echo 1 &gt; events/uprobes/enable<br /> echo 1 &gt; tracing_on<br /> ```<br /> <br /> 6. run `test`, and kasan will report error.<br /> ==================================================================<br /> BUG: KASAN: use-after-free in strncpy_from_user+0x1d6/0x1f0<br /> 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<br /> Hardware name: Red Hat KVM, BIOS 1.16.0-4.al8 04/01/2014<br /> Call Trace:<br /> <br /> dump_stack_lvl+0x55/0x70<br /> print_address_description.constprop.0+0x27/0x310<br /> kasan_report+0x10f/0x120<br /> ? strncpy_from_user+0x1d6/0x1f0<br /> strncpy_from_user+0x1d6/0x1f0<br /> ? rmqueue.constprop.0+0x70d/0x2ad0<br /> process_fetch_insn+0xb26/0x1470<br /> ? __pfx_process_fetch_insn+0x10/0x10<br /> ? _raw_spin_lock+0x85/0xe0<br /> ? __pfx__raw_spin_lock+0x10/0x10<br /> ? __pte_offset_map+0x1f/0x2d0<br /> ? unwind_next_frame+0xc5f/0x1f80<br /> ? arch_stack_walk+0x68/0xf0<br /> ? is_bpf_text_address+0x23/0x30<br /> ? kernel_text_address.part.0+0xbb/0xd0<br /> ? __kernel_text_address+0x66/0xb0<br /> ? unwind_get_return_address+0x5e/0xa0<br /> ? __pfx_stack_trace_consume_entry+0x10/0x10<br /> ? arch_stack_walk+0xa2/0xf0<br /> ? _raw_spin_lock_irqsave+0x8b/0xf0<br /> ? __pfx__raw_spin_lock_irqsave+0x10/0x10<br /> ? depot_alloc_stack+0x4c/0x1f0<br /> ? _raw_spin_unlock_irqrestore+0xe/0x30<br /> ? stack_depot_save_flags+0x35d/0x4f0<br /> ? kasan_save_stack+0x34/0x50<br /> ? kasan_save_stack+0x24/0x50<br /> ? mutex_lock+0x91/0xe0<br /> ? __pfx_mutex_lock+0x10/0x10<br /> prepare_uprobe_buffer.part.0+0x2cd/0x500<br /> uprobe_dispatcher+0x2c3/0x6a0<br /> ? __pfx_uprobe_dispatcher+0x10/0x10<br /> ? __kasan_slab_alloc+0x4d/0x90<br /> handler_chain+0xdd/0x3e0<br /> handle_swbp+0x26e/0x3d0<br /> ? __pfx_handle_swbp+0x10/0x10<br /> ? uprobe_pre_sstep_notifier+0x151/0x1b0<br /> irqentry_exit_to_user_mode+0xe2/0x1b0<br /> asm_exc_int3+0x39/0x40<br /> RIP: 0033:0x401199<br /> 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<br /> RSP: 002b:00007ffdf00576a8 EFLAGS: 00000206<br /> RAX: 00007ffdf00576b0 RBX: 0000000000000000 RCX: 0000000000000ff2<br /> RDX: 0000000000000ffc RSI: 0000000000000ffd RDI: 00007ffdf00576b0<br /> RBP: 00007ffdf00586b0 R08: 00007feb2f9c0d20 R09: 00007feb2f9c0d20<br /> R10: 0000000000000001 R11: 0000000000000202 R12: 0000000000401040<br /> R13: 00007ffdf0058780 R14: 0000000000000000 R15: 0000000000000000<br /> <br /> <br /> This commit enforces the buffer&amp;#39;s maxlen less than a page-size to avoid<br /> store_trace_args() out-of-memory access.