[PATCH 06/23] perf tools: Use mkostemp() for O_CLOEXEC on temporary files

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

mkstemp() creates file descriptors without the close-on-exec flag.
These fds leak to child processes spawned during symbol resolution
(addr2line, objdump), wasting descriptors and potentially exposing
temporary file contents.

Replace mkstemp() with mkostemp(tmpbuf, O_CLOEXEC) at all three
call sites:

  - filename__decompress() in dso.c
  - read_gnu_debugdata() in symbol-elf.c
  - kcore__init() in symbol-elf.c

Fixes: 42b3fa670825983f ("perf tools: Introduce dso__decompress_kmodule_{fd,path}")
Fixes: b10f74308e130527 ("perf symbol: Support .gnu_debugdata for symbols")
Fixes: afba19d9dc8eba66 ("perf symbols: Workaround objdump difficulties with kcore")
Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx>
Assisted-by: Claude Opus 4.6 <noreply@xxxxxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/dso.c        | 2 +-
 tools/perf/util/symbol-elf.c | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index fb2e78fe2aa8eb94..ee06a252a54d338d 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -346,7 +346,7 @@ int filename__decompress(const char *name, char *pathname,
 	if (!compressions[comp].is_compressed(name))
 		return open(name, O_RDONLY | O_CLOEXEC);
 
-	fd = mkstemp(tmpbuf);
+	fd = mkostemp(tmpbuf, O_CLOEXEC);
 	if (fd < 0) {
 		*err = errno;
 		return -1;
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 51e7cfe0f5934875..36a0304707e13138 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1119,9 +1119,9 @@ static Elf *read_gnu_debugdata(struct dso *dso, Elf *elf, const char *name, int
 		return NULL;
 	}
 
-	temp_fd = mkstemp(temp_filename);
+	temp_fd = mkostemp(temp_filename, O_CLOEXEC);
 	if (temp_fd < 0) {
-		pr_debug("%s: mkstemp: %m\n", __func__);
+		pr_debug("%s: mkostemp: %m\n", __func__);
 		*dso__load_errno(dso) = -errno;
 		fclose(wrapped);
 		return NULL;
@@ -1993,7 +1993,7 @@ static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
 	kcore->elfclass = elfclass;
 
 	if (temp)
-		kcore->fd = mkstemp(filename);
+		kcore->fd = mkostemp(filename, O_CLOEXEC);
 	else
 		kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, 0400);
 	if (kcore->fd == -1)
-- 
2.54.0