Contributed by Peter N. M. Hansteen on from the freeing the chunks dept.
In a message to
tech@, Otto Moerbeek (
otto@) announced the new functionality:
Subject: malloc leak detection available in -current From: Otto Moerbeek <otto () drijf ! net> Date: 2023-04-17 6:43:19 Hi, OpenBSD current now has built-in malloc leak detection. Make sure you run current and have debug symbols (OpenBSD base libraries have debug symbols, compile your own program with -g).
To record the leak report: $ MALLOC_OPTIONS=D ktrace -tu a.out To view the leak report: $ kdump -u malloc Example output: ******** Start dump a.out ******* M=8 I=1 F=0 U=0 J=1 R=0 X=0 C=0 cache=64 G=0 Leak report: f sum # avg 0x0 1088864 9722 112 addr2line -e '?' 0x0 0xf4b73093c 31136 278 112 addr2line -e a.out 0x1093c ******** End dump a.out ******* $ addr2line -e a.out 0x1093c /home/otto/x.c:6 Some additional info: The null "f" values (call sites) are due to the sampling nature of small allocations. Recording all call sites of all potential leaks introduces too much overhead. Note that aggresssive optimizations might confuse the line numbers reported. For -static programs, compile with -nopie to make addr2line work. In some cases will want to use the packaged version of addr2line (gaddr2line, in the binutils package) as the base addr2line does not grok all debug info formats. -Otto
This represents one important step in the ongoing work of making OpenBSD the better environment for developing secure, well behaved code.
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