[PATCH] libbpf: set close-on-exec flag on gzopen

[PATCH] libbpf: set close-on-exec flag on gzopen

[Martin Kelly]

From: Marco Vedovati <marco.vedovati@crowdstrike.com>

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.

Signed-off-by: Marco Vedovati <marco.vedovati@crowdstrike.com>
---
 tools/lib/bpf/libbpf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 17883f5a44b9..b14a4376a86e 100644
--- 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");
-- 
2.34.1

Re: [PATCH] libbpf: set close-on-exec flag on gzopen

[Stanislav Fomichev]

On 08/10, Martin Kelly wrote:
> From: Marco Vedovati <marco.vedovati@crowdstrike.com>
> 
> 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.

We do have fopen(, "re") all over the place; gzopen seem to pass mode
to fopen.

Acked-by: Stanislav Fomichev <sdf@google.com>
Fixes: 8601fd422148 ("libbpf: Allow to augment system Kconfig through extra optional config")

For fixes, not sure whether anybody actually builds libbpf from the kernel
tree...