From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Yuan Chen <chenyuan@kylinos.cn>,
	Andrii Nakryiko <andrii@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.12 1117/1376] bpftool: Fix double close in map dump
Date: Sat, 12 Sep 2026 08:59:03 +0200
Message-ID: <20260912065632.456403971@linuxfoundation.org>
In-Reply-To: <20260912065607.535295758@linuxfoundation.org>
References: <20260912065607.535295758@linuxfoundation.org>
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6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yuan Chen <chenyuan@kylinos.cn>

[ Upstream commit 259d60f5bfa41056fe01cbf2ba3f6f0331865a16 ]

map_dump() closes the map fd in its error path, and do_dump() then
closes the same fd again after a successful dump. Closing an already
closed fd leaves errno set to EBADF, which poisons later errno checks
such as the batch file read check in do_batch(). Let do_dump() own the
fd and remove the close from map_dump().

The same double-close pattern exists in do_show_subset(): both
show_map_close_json() and show_map_close_plain() already close the fd,
so drop the extra close() there as well.

Also propagate the error when bpf_map_get_info_by_fd() fails on a
subsequent map in do_dump(): set err = -1 before breaking out of the
loop, so a later failure is not silently hidden after an earlier
iteration succeeded.

Fixes: 99f9863a0c45f ("bpftool: Match maps by name")
Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260810142224.2907373-2-chenyuan_fl@163.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/bpf/bpftool/map.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 332e040677154..a9c8af7db19ae 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -659,8 +659,6 @@ static int do_show_subset(int argc, char **argv)
 			show_map_close_json(fds[i], &info);
 		else
 			show_map_close_plain(fds[i], &info);
-
-		close(fds[i]);
 	}
 	if (json_output && nb_fds > 1)
 		jsonw_end_array(json_wtr);	/* root array */
@@ -892,7 +890,6 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr,
 exit_free:
 	free(key);
 	free(value);
-	close(fd);
 	free_map_kv_btf(btf);
 
 	return err;
@@ -941,6 +938,7 @@ static int do_dump(int argc, char **argv)
 	for (i = 0; i < nb_fds; i++) {
 		if (bpf_map_get_info_by_fd(fds[i], &info, &len)) {
 			p_err("can't get map info: %s", strerror(errno));
+			err = -1;
 			break;
 		}
 		err = map_dump(fds[i], &info, wtr, nb_fds > 1);
-- 
2.53.0