From 66d7e39e49b0dd57610c9b63afc65b4d5690983b Mon Sep 17 00:00:00 2001 From: Yichong Chen Date: Wed, 24 Jun 2026 10:50:54 +0800 Subject: [PATCH] tools/bpf/bpftool: Reset vmlinux BTF after map commands get_map_kv_btf() caches the vmlinux BTF object when a map uses btf_vmlinux_value_type_id. map dump released that object when the command completed, but left the global pointer stale. The same cached object can also be returned to print_key_value(), which freed it directly. That leaves btf_vmlinux dangling before the command cleanup path runs. Use free_map_kv_btf() for per-entry cleanup, and reset the cached btf_vmlinux pointer when the map command releases the object. This keeps batch mode from reusing a freed BTF object. Fixes: 4e1ea33292ff ("bpftool: Support dumping a map with btf_vmlinux_value_type_id") Signed-off-by: Yichong Chen Signed-off-by: Andrii Nakryiko Reviewed-by: Emil Tsalapatis Link: https://lore.kernel.org/bpf/9072F43B3F74DF91+20260624025055.1574875-2-chenyichong@uniontech.com --- tools/bpf/bpftool/map.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index 71a45d96617e..6b9649294ca1 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -790,6 +790,12 @@ static int maps_have_btf(int *fds, int nb_fds) static struct btf *btf_vmlinux; +static void free_btf_vmlinux(void) +{ + btf__free(btf_vmlinux); + btf_vmlinux = NULL; +} + static int get_map_kv_btf(const struct bpf_map_info *info, struct btf **btf) { int err = 0; @@ -958,7 +964,7 @@ static int do_dump(int argc, char **argv) close(fds[i]); exit_free: free(fds); - btf__free(btf_vmlinux); + free_btf_vmlinux(); return err; } @@ -1049,7 +1055,7 @@ static void print_key_value(struct bpf_map_info *info, void *key, btf_wtr = get_btf_writer(); if (!btf_wtr) { p_info("failed to create json writer for btf. falling back to plain output"); - btf__free(btf); + free_map_kv_btf(btf); btf = NULL; print_entry_plain(info, key, value); } else { @@ -1065,7 +1071,7 @@ static void print_key_value(struct bpf_map_info *info, void *key, } else { print_entry_plain(info, key, value); } - btf__free(btf); + free_map_kv_btf(btf); } static int do_lookup(int argc, char **argv)