Syzkaller reported a general protection fault due to a NULL pointer dereference in print_reg_state() when accessing reg->map_ptr without checking if it is NULL. The existing code assumes reg->map_ptr is always valid before dereferencing reg->map_ptr->name, reg->map_ptr->key_size, and reg->map_ptr->value_size. Fix this by adding explicit NULL checks before accessing reg->map_ptr and its members. This prevents crashes when reg->map_ptr is NULL, improving the robustness of the BPF verifier's verbose logging. Reported-by: syzbot+d36d5ae81e1b0a53ef58@syzkaller.appspotmail.com Signed-off-by: Brahmajit Das --- kernel/bpf/log.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 38050f4ee400..b38efbbf22cf 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -716,11 +716,12 @@ static void print_reg_state(struct bpf_verifier_env *env, if (type_is_non_owning_ref(reg->type)) verbose_a("%s", "non_own_ref"); if (type_is_map_ptr(t)) { - if (reg->map_ptr->name[0]) + if (reg->map_ptr != NULL && reg->map_ptr->name[0] != '\0') verbose_a("map=%s", reg->map_ptr->name); - verbose_a("ks=%d,vs=%d", - reg->map_ptr->key_size, - reg->map_ptr->value_size); + if (reg->map_ptr != NULL) + verbose_a("ks=%d,vs=%d", + reg->map_ptr->key_size, + reg->map_ptr->value_size); } if (t != SCALAR_VALUE && reg->off) { verbose_a("off="); -- 2.51.0