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1.. SPDX-License-Identifier: GPL-2.02 3.. include:: ../disclaimer-zh_CN.rst4 5:Original: Documentation/dev-tools/ubsan.rst6:Translator: Dongliang Mu <dzm91@hust.edu.cn>7 8未定义行为消毒剂 - UBSAN9====================================10 11UBSAN是一种动态未定义行为检查工具。12 13UBSAN使用编译时插桩捕捉未定义行为。编译器在可能导致未定义行为的操作前插入特定14检测代码。如果检查失败，即检测到未定义行为，__ubsan_handle_* 函数将被调用打印15错误信息。16 17GCC自4.9.x [1_] （详见 ``-fsanitize=undefined`` 选项及其子选项）版本后引入这18一特性。GCC 5.x 版本实现了更多检查器 [2_]。19 20报告样例21--------------22 23::24 25 ================================================================================26 UBSAN: Undefined behaviour in ../include/linux/bitops.h:110:3327 shift exponent 32 is to large for 32-bit type 'unsigned int'28 CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc1+ #2629 0000000000000000 ffffffff82403cc8 ffffffff815e6cd6 000000000000000130 ffffffff82403cf8 ffffffff82403ce0 ffffffff8163a5ed 000000000000002031 ffffffff82403d78 ffffffff8163ac2b ffffffff815f0001 000000000000000232 Call Trace:33 [<ffffffff815e6cd6>] dump_stack+0x45/0x5f34 [<ffffffff8163a5ed>] ubsan_epilogue+0xd/0x4035 [<ffffffff8163ac2b>] __ubsan_handle_shift_out_of_bounds+0xeb/0x13036 [<ffffffff815f0001>] ? radix_tree_gang_lookup_slot+0x51/0x15037 [<ffffffff8173c586>] _mix_pool_bytes+0x1e6/0x48038 [<ffffffff83105653>] ? dmi_walk_early+0x48/0x5c39 [<ffffffff8173c881>] add_device_randomness+0x61/0x13040 [<ffffffff83105b35>] ? dmi_save_one_device+0xaa/0xaa41 [<ffffffff83105653>] dmi_walk_early+0x48/0x5c42 [<ffffffff831066ae>] dmi_scan_machine+0x278/0x4b443 [<ffffffff8111d58a>] ? vprintk_default+0x1a/0x2044 [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x12045 [<ffffffff830b2240>] setup_arch+0x405/0xc2c46 [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x12047 [<ffffffff830ae053>] start_kernel+0x83/0x49a48 [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x12049 [<ffffffff830ad386>] x86_64_start_reservations+0x2a/0x2c50 [<ffffffff830ad4f3>] x86_64_start_kernel+0x16b/0x17a51 ================================================================================52 53用法54-----55 56使用如下内核配置启用UBSAN::57 58 CONFIG_UBSAN=y59 60使用如下内核配置检查整个内核::61 62 CONFIG_UBSAN_SANITIZE_ALL=y63 64为了在特定文件或目录启动代码插桩，需要在相应的内核Makefile中添加一行类似内容:65 66- 单文件（如main.o）::67 68 UBSAN_SANITIZE_main.o := y69 70- 一个目录中的所有文件::71 72 UBSAN_SANITIZE := y73 74即使设置了``CONFIG_UBSAN_SANITIZE_ALL=y``，为了避免文件被插桩，可使用::75 76 UBSAN_SANITIZE_main.o := n77 78与::79 80 UBSAN_SANITIZE := n81 82未对齐的内存访问检测可通过开启独立选项 - CONFIG_UBSAN_ALIGNMENT 检测。83该选项在支持未对齐访问的架构上(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y)84默认为关闭。该选项仍可通过内核配置启用，但它将产生大量的UBSAN报告。85 86参考文献87----------88 89.. _1: https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html90.. _2: https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html91.. _3: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html92