diff options
| -rw-r--r-- | kernel/bpf/btf.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 4872d2a6c42d..71f9143fe90f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -1787,7 +1787,16 @@ static void btf_free_id(struct btf *btf) * of the _bh() version. */ spin_lock_irqsave(&btf_idr_lock, flags); - idr_remove(&btf_idr, btf->id); + if (btf->id) { + idr_remove(&btf_idr, btf->id); + /* + * Clear the id here to make this function idempotent, since it will get + * called a couple of times for module BTFs: on module unload, and then + * the final btf_put(). btf_alloc_id() starts IDs with 1, so we can use + * 0 as sentinel value. + */ + WRITE_ONCE(btf->id, 0); + } spin_unlock_irqrestore(&btf_idr_lock, flags); } @@ -8115,7 +8124,7 @@ static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp) { const struct btf *btf = filp->private_data; - seq_printf(m, "btf_id:\t%u\n", btf->id); + seq_printf(m, "btf_id:\t%u\n", READ_ONCE(btf->id)); } #endif @@ -8197,7 +8206,7 @@ int btf_get_info_by_fd(const struct btf *btf, if (copy_from_user(&info, uinfo, info_copy)) return -EFAULT; - info.id = btf->id; + info.id = READ_ONCE(btf->id); ubtf = u64_to_user_ptr(info.btf); btf_copy = min_t(u32, btf->data_size, info.btf_size); if (copy_to_user(ubtf, btf->data, btf_copy)) @@ -8260,7 +8269,7 @@ int btf_get_fd_by_id(u32 id) u32 btf_obj_id(const struct btf *btf) { - return btf->id; + return READ_ONCE(btf->id); } bool btf_is_kernel(const struct btf *btf) @@ -8382,6 +8391,13 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, if (btf_mod->module != module) continue; + /* + * For modules, we do the freeing of BTF IDR as soon as + * module goes away to disable BTF discovery, since the + * btf_try_get_module() on such BTFs will fail. This may + * be called again on btf_put(), but it's ok to do so. + */ + btf_free_id(btf_mod->btf); list_del(&btf_mod->list); if (btf_mod->sysfs_attr) sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr); |