Add regression coverage for bpf_refcount_acquire() on graph-node-derived pointers.
The rejected case passes a popped list node pointer directly to bpf_refcount_acquire(), which must fail because the pointer carries a non-zero fixed offset. Signed-off-by: Yiyang Chen <[email protected]> --- .../bpf/progs/refcounted_kptr_fail.c | 34 +++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c b/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c index 7247a20c0..024ef2aae 100644 --- a/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c +++ b/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c @@ -13,12 +13,20 @@ struct node_acquire { struct bpf_refcount refcount; }; +struct node_refcounted { + long key; + struct bpf_list_node list; + struct bpf_refcount refcount; +}; + extern void bpf_rcu_read_lock(void) __ksym; extern void bpf_rcu_read_unlock(void) __ksym; #define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8))) private(A) struct bpf_spin_lock glock; private(A) struct bpf_rb_root groot __contains(node_acquire, node); +private(B) struct bpf_spin_lock lock; +private(B) struct bpf_list_head head __contains(node_refcounted, list); static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b) { @@ -93,6 +101,32 @@ long rbtree_refcounted_node_ref_escapes_owning_input(void *ctx) return 0; } +SEC("?tc") +__failure __msg("dereference of modified ptr_ ptr R1") +long refcount_acquire_list_node_offset(void *ctx) +{ + struct node_refcounted *node, *base, *ref; + struct bpf_list_node *list_node; + + node = bpf_obj_new(typeof(*node)); + if (!node) + return 1; + + bpf_spin_lock(&lock); + bpf_list_push_front(&head, &node->list); + list_node = bpf_list_pop_front(&head); + bpf_spin_unlock(&lock); + if (!list_node) + return 2; + + base = container_of(list_node, struct node_refcounted, list); + ref = bpf_refcount_acquire(list_node); + if (ref) + bpf_obj_drop(ref); + bpf_obj_drop(base); + return 0; +} + SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") __failure __msg("function calls are not allowed while holding a lock") int BPF_PROG(rbtree_fail_sleepable_lock_across_rcu, -- 2.34.1
