From: xtkoba+ruby@... Date: 2021-02-24T23:23:57+00:00 Subject: [ruby-core:102599] [Ruby master Bug#17656] Improper functions shown in C level backtrace information Issue #17656 has been reported by xtkoba (Tee KOBAYASHI). ---------------------------------------- Bug #17656: Improper functions shown in C level backtrace information https://bugs.ruby-lang.org/issues/17656 * Author: xtkoba (Tee KOBAYASHI) * Status: Open * Priority: Normal * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN ---------------------------------------- The following is an example of C backtrace output on aarch64-linux, where `sig_do_nothing` is shown in spite of segfault: ``` -- C level backtrace information ------------------------------------------- /var/tmp/build.debug/aarch64.clang.O0/lib/libruby.so.3.0(rb_print_backtrace+0x24) [0x5500b86c74] vm_dump.c:758 /var/tmp/build.debug/aarch64.clang.O0/lib/libruby.so.3.0(rb_vm_bugreport+0xa8) [0x5500b86d38] vm_dump.c:999 /var/tmp/build.debug/aarch64.clang.O0/lib/libruby.so.3.0(rb_bug_for_fatal_signal+0x108) [0x550092fb7c] error.c:786 /var/tmp/build.debug/aarch64.clang.O0/lib/libruby.so.3.0(sig_do_nothing+0x0) [0x5500abfa90] signal.c:960 /var/tmp/build.debug/aarch64.clang.O0/lib/libruby.so.3.0(sigsegv) (null):0 [0x50c810] (...) ``` This happens because `backtrace(3)` fills the buffer with the return addresses retrieved from stack frames. A workaround is to subtract 1 from each return address [1], as in the attached patch. [1] http://lists.dwarfstd.org/pipermail/dwarf-discuss-dwarfstd.org/2020-July/004694.html ---Files-------------------------------- ruby-backtrace-address-off-by-1.patch (470 Bytes) -- https://bugs.ruby-lang.org/ Unsubscribe: