From: Michael Petlan Date: Tue, 19 May 2026 22:38:55 +0000 (+0200) Subject: perf build-id: Fix off-by-one bug when printing kernel/module build-id X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=017bca78e4d72b1ff027d368c20a1b2c654edaf7;p=thirdparty%2Fkernel%2Fstable.git perf build-id: Fix off-by-one bug when printing kernel/module build-id When changing sprintf functions to snprintf, one byte got lost. Since snprintf ones do not handle the '\0' terminating character, the number of printed characters is 40, while sizeof(sbuild_id) is 41, including the terminating '\0' character. This makes the later check fail so that nothing is printed. Fix that. Before: [Michael@Carbon ~]$ perf buildid-list -k [Michael@Carbon ~]$ After: [Michael@Carbon ~]$ perf buildid-list -k a527806324d543c4bc3ff2f9c9519d494fed5f68 [Michael@Carbon ~]$ Fixes: fccaaf6fbbc59910 ("perf build-id: Change sprintf functions to snprintf") Signed-off-by: Michael Petlan Tested-by: Ian Rogers Cc: Ian Rogers Cc: Namhyung Kim Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/builtin-buildid-list.c b/tools/perf/builtin-buildid-list.c index a91bbb34ac94..e0881b0ac38f 100644 --- a/tools/perf/builtin-buildid-list.c +++ b/tools/perf/builtin-buildid-list.c @@ -61,7 +61,7 @@ static int sysfs__fprintf_build_id(FILE *fp) int ret; ret = sysfs__snprintf_build_id("/", sbuild_id, sizeof(sbuild_id)); - if (ret != sizeof(sbuild_id)) + if (ret + 1 != sizeof(sbuild_id)) return ret < 0 ? ret : -EINVAL; return fprintf(fp, "%s\n", sbuild_id); @@ -73,7 +73,7 @@ static int filename__fprintf_build_id(const char *name, FILE *fp) int ret; ret = filename__snprintf_build_id(name, sbuild_id, sizeof(sbuild_id)); - if (ret != sizeof(sbuild_id)) + if (ret + 1 != sizeof(sbuild_id)) return ret < 0 ? ret : -EINVAL; return fprintf(fp, "%s\n", sbuild_id);