^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) The Undefined Behavior Sanitizer - UBSAN
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) ========================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) UBSAN is a runtime undefined behaviour checker.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) UBSAN uses compile-time instrumentation to catch undefined behavior (UB).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) Compiler inserts code that perform certain kinds of checks before operations
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) that may cause UB. If check fails (i.e. UB detected) __ubsan_handle_*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) function called to print error message.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) GCC has that feature since 4.9.x [1_] (see ``-fsanitize=undefined`` option and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) its suboptions). GCC 5.x has more checkers implemented [2_].
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) Report example
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) --------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) ::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) ================================================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) UBSAN: Undefined behaviour in ../include/linux/bitops.h:110:33
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) shift exponent 32 is to large for 32-bit type 'unsigned int'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc1+ #26
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 0000000000000000 ffffffff82403cc8 ffffffff815e6cd6 0000000000000001
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) ffffffff82403cf8 ffffffff82403ce0 ffffffff8163a5ed 0000000000000020
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) ffffffff82403d78 ffffffff8163ac2b ffffffff815f0001 0000000000000002
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) Call Trace:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) [<ffffffff815e6cd6>] dump_stack+0x45/0x5f
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) [<ffffffff8163a5ed>] ubsan_epilogue+0xd/0x40
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) [<ffffffff8163ac2b>] __ubsan_handle_shift_out_of_bounds+0xeb/0x130
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) [<ffffffff815f0001>] ? radix_tree_gang_lookup_slot+0x51/0x150
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) [<ffffffff8173c586>] _mix_pool_bytes+0x1e6/0x480
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) [<ffffffff83105653>] ? dmi_walk_early+0x48/0x5c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) [<ffffffff8173c881>] add_device_randomness+0x61/0x130
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) [<ffffffff83105b35>] ? dmi_save_one_device+0xaa/0xaa
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) [<ffffffff83105653>] dmi_walk_early+0x48/0x5c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) [<ffffffff831066ae>] dmi_scan_machine+0x278/0x4b4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) [<ffffffff8111d58a>] ? vprintk_default+0x1a/0x20
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) [<ffffffff830b2240>] setup_arch+0x405/0xc2c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) [<ffffffff830ae053>] start_kernel+0x83/0x49a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) [<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) [<ffffffff830ad386>] x86_64_start_reservations+0x2a/0x2c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) [<ffffffff830ad4f3>] x86_64_start_kernel+0x16b/0x17a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) ================================================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) Usage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) -----
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) To enable UBSAN configure kernel with::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) CONFIG_UBSAN=y
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) and to check the entire kernel::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) CONFIG_UBSAN_SANITIZE_ALL=y
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) To enable instrumentation for specific files or directories, add a line
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) similar to the following to the respective kernel Makefile:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) - For a single file (e.g. main.o)::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) UBSAN_SANITIZE_main.o := y
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) - For all files in one directory::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) UBSAN_SANITIZE := y
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) To exclude files from being instrumented even if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) ``CONFIG_UBSAN_SANITIZE_ALL=y``, use::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) UBSAN_SANITIZE_main.o := n
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) and::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) UBSAN_SANITIZE := n
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) Detection of unaligned accesses controlled through the separate option -
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) CONFIG_UBSAN_ALIGNMENT. It's off by default on architectures that support
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) unaligned accesses (CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y). One could
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) still enable it in config, just note that it will produce a lot of UBSAN
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) reports.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) References
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) ----------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) .. _1: https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) .. _2: https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) .. _3: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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