libbpf: Set close-on-exec flag on gzopen

Enable the close-on-exec flag when using gzopen. This is especially important
for multithreaded programs making use of libbpf, where a fork + exec could
race with libbpf library calls, potentially resulting in a file descriptor
leaked to the new process. This got missed in 59842c5451fe ("libbpf: Ensure
libbpf always opens files with O_CLOEXEC").

Fixes: 59842c5451fe ("libbpf: Ensure libbpf always opens files with O_CLOEXEC")
Signed-off-by: Marco Vedovati <marco.vedovati@crowdstrike.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230810214350.106301-1-martin.kelly@crowdstrike.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 17883f5..b14a437 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1978,9 +1978,9 @@ static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
                return -ENAMETOOLONG;
 
        /* gzopen also accepts uncompressed files. */
-       file = gzopen(buf, "r");
+       file = gzopen(buf, "re");
        if (!file)
-               file = gzopen("/proc/config.gz", "r");
+               file = gzopen("/proc/config.gz", "re");
 
        if (!file) {
                pr_warn("failed to open system Kconfig\n");