1 .. SPDX-License-Identifier: GPL-2.0 2 3 .. include:: ../disclaimer-zh_CN.rst 4 5 :Original: Documentation/dev-tools/ubsan.rst 6 :Translator: Dongliang Mu <dzm91@hust.edu.cn> 7 8 未定义行为消毒剂 - UBSAN 9 ==================================== 10 11 UBSAN是一种动态未定义行为检查工具。 12 13 UBSAN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 17 GCC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:110:33 27 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+ #26 29 0000000000000000 ffffffff82403cc8 ffffffff815e6cd6 0000000000000001 30 ffffffff82403cf8 ffffffff82403ce0 ffffffff8163a5ed 0000000000000020 31 ffffffff82403d78 ffffffff8163ac2b ffffffff815f0001 0000000000000002 32 Call Trace: 33 [<ffffffff815e6cd6>] dump_stack+0x45/0x5f 34 [<ffffffff8163a5ed>] ubsan_epilogue+0xd/0x40 35 [<ffffffff8163ac2b>] __ubsan_handle_shift_out_of_bounds+0xeb/0x130 36 [<ffffffff815f0001>] ? radix_tree_gang_lookup_slot+0x51/0x150 37 [<ffffffff8173c586>] _mix_pool_bytes+0x1e6/0x480 38 [<ffffffff83105653>] ? dmi_walk_early+0x48/0x5c 39 [<ffffffff8173c881>] add_device_randomness+0x61/0x130 40 [<ffffffff83105b35>] ? dmi_save_one_device+0xaa/0xaa 41 [<ffffffff83105653>] dmi_walk_early+0x48/0x5c 42 [<ffffffff831066ae>] dmi_scan_machine+0x278/0x4b4 43 [<ffffffff8111d58a>] ? vprintk_default+0x1a/0x20 44 [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120 45 [<ffffffff830b2240>] setup_arch+0x405/0xc2c 46 [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120 47 [<ffffffff830ae053>] start_kernel+0x83/0x49a 48 [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120 49 [<ffffffff830ad386>] x86_64_start_reservations+0x2a/0x2c 50 [<ffffffff830ad4f3>] x86_64_start_kernel+0x16b/0x17a 51 ================================================================================ 52 53 用法 54 ----- 55 56 使用如下内核配置启用UBSAN:: 57 58 CONFIG_UBSAN=y 59 60 使用如下内核配置检查整个内核:: 61 62 CONFIG_UBSAN_SANITIZE_ALL=y 63 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 := y 69 70 - 一个目录中的所有文件:: 71 72 UBSAN_SANITIZE := y 73 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 := n 77 78 与:: 79 80 UBSAN_SANITIZE := n 81 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.html 90 .. _2: https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html 91 .. _3: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
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