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| 1 | +.. SPDX-License-Identifier: GPL-2.0 |
| 2 | +
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| 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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