92 lines
3.3 KiB
ReStructuredText
92 lines
3.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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.. include:: ../disclaimer-zh_CN.rst
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:Original: Documentation/dev-tools/ubsan.rst
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:Translator: Dongliang Mu <dzm91@hust.edu.cn>
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未定义行为消毒剂 - UBSAN
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====================================
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UBSAN是一种动态未定义行为检查工具。
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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
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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
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错误信息。
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GCC自4.9.x [1_] （详见 ``-fsanitize=undefined`` 选项及其子选项）版本后引入这
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一特性。GCC 5.x 版本实现了更多检查器 [2_]。
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报告样例
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--------------
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::
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================================================================================
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UBSAN: Undefined behaviour in ../include/linux/bitops.h:110:33
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shift exponent 32 is to large for 32-bit type 'unsigned int'
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CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc1+ #26
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0000000000000000 ffffffff82403cc8 ffffffff815e6cd6 0000000000000001
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ffffffff82403cf8 ffffffff82403ce0 ffffffff8163a5ed 0000000000000020
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ffffffff82403d78 ffffffff8163ac2b ffffffff815f0001 0000000000000002
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Call Trace:
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[<ffffffff815e6cd6>] dump_stack+0x45/0x5f
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[<ffffffff8163a5ed>] ubsan_epilogue+0xd/0x40
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[<ffffffff8163ac2b>] __ubsan_handle_shift_out_of_bounds+0xeb/0x130
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[<ffffffff815f0001>] ? radix_tree_gang_lookup_slot+0x51/0x150
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[<ffffffff8173c586>] _mix_pool_bytes+0x1e6/0x480
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[<ffffffff83105653>] ? dmi_walk_early+0x48/0x5c
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[<ffffffff8173c881>] add_device_randomness+0x61/0x130
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[<ffffffff83105b35>] ? dmi_save_one_device+0xaa/0xaa
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[<ffffffff83105653>] dmi_walk_early+0x48/0x5c
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[<ffffffff831066ae>] dmi_scan_machine+0x278/0x4b4
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[<ffffffff8111d58a>] ? vprintk_default+0x1a/0x20
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[<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
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[<ffffffff830b2240>] setup_arch+0x405/0xc2c
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[<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
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[<ffffffff830ae053>] start_kernel+0x83/0x49a
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[<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
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[<ffffffff830ad386>] x86_64_start_reservations+0x2a/0x2c
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[<ffffffff830ad4f3>] x86_64_start_kernel+0x16b/0x17a
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================================================================================
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用法
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-----
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使用如下内核配置启用UBSAN::
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CONFIG_UBSAN=y
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使用如下内核配置检查整个内核::
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CONFIG_UBSAN_SANITIZE_ALL=y
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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:
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- 单文件（如main.o）::
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UBSAN_SANITIZE_main.o := y
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- 一个目录中的所有文件::
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UBSAN_SANITIZE := y
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即使设置了``CONFIG_UBSAN_SANITIZE_ALL=y``，为了避免文件被插桩，可使用::
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UBSAN_SANITIZE_main.o := n
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与::
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UBSAN_SANITIZE := n
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未对齐的内存访问检测可通过开启独立选项 - CONFIG_UBSAN_ALIGNMENT 检测。
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该选项在支持未对齐访问的架构上(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y)
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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。
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参考文献
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----------
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.. _1: https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html
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.. _2: https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
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.. _3: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
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