From f3013f7ed465479e60c1ab1921a5718fc541cc3b Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 1 Oct 2020 11:34:19 +0200 Subject: perf trace: Fix off by ones in memset() after realloc() in arches using libaudit 'perf trace ls' started crashing after commit d21cb73a9025 on !HAVE_SYSCALL_TABLE_SUPPORT configs (armv7l here) like this: 0 strlen () at ../sysdeps/arm/armv6t2/strlen.S:126 1 0xb6800780 in __vfprintf_internal (s=0xbeff9908, s@entry=0xbeff9900, format=0xa27160 "]: %s()", ap=..., mode_flags=) at vfprintf-internal.c:1688 ... 5 0x0056ecdc in fprintf (__fmt=0xa27160 "]: %s()", __stream=) at /usr/include/bits/stdio2.h:100 6 trace__sys_exit (trace=trace@entry=0xbeffc710, evsel=evsel@entry=0xd968d0, event=, sample=sample@entry=0xbeffc3e8) at builtin-trace.c:2475 7 0x00566d40 in trace__handle_event (sample=0xbeffc3e8, event=, trace=0xbeffc710) at builtin-trace.c:3122 ... 15 main (argc=2, argv=0xbefff6e8) at perf.c:538 It is because memset in trace__read_syscall_info zeroes wrong memory: 1) when initializing for the first time, it does not reset the last id. 2) in other cases, it resets the last id of previous buffer. ad 1) it causes the crash above as sc->name used in the fprintf above contains garbage. ad 2) it sets nonexistent from true back to false for id 11 here. Not sure, what the consequences are. So fix it by introducing a special case for the initial initialization and do the right +1 in both cases. Fixes: d21cb73a9025 ("perf trace: Grow the syscall table as needed when using libaudit") Signed-off-by: Jiri Slaby Cc: Adrian Hunter Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/20201001093419.15761-1-jslaby@suse.cz Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'tools/perf') diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index bea461b6f937..44a75f234db1 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1762,7 +1762,11 @@ static int trace__read_syscall_info(struct trace *trace, int id) if (table == NULL) return -ENOMEM; - memset(table + trace->sctbl->syscalls.max_id, 0, (id - trace->sctbl->syscalls.max_id) * sizeof(*sc)); + // Need to memset from offset 0 and +1 members if brand new + if (trace->syscalls.table == NULL) + memset(table, 0, (id + 1) * sizeof(*sc)); + else + memset(table + trace->sctbl->syscalls.max_id + 1, 0, (id - trace->sctbl->syscalls.max_id) * sizeof(*sc)); trace->syscalls.table = table; trace->sctbl->syscalls.max_id = id; -- cgit v1.2.3