Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2024-06-05

We've added 8 non-merge commits during the last 6 day(s) which contain
a total of 9 files changed, 34 insertions(+), 35 deletions(-).

The main changes are:

1) Fix a potential use-after-free in bpf_link_free when the link uses
   dealloc_deferred to free the link object but later still tests for
   presence of link->ops->dealloc, from Cong Wang.

2) Fix BPF test infra to set the run context for rawtp test_run callback
   where syzbot reported a crash, from Jiri Olsa.

3) Fix bpf_session_cookie BTF_ID in the special_kfunc_set list to exclude
   it for the case of !CONFIG_FPROBE, also from Jiri Olsa.

4) Fix a Coverity static analysis report to not close() a link_fd of -1
   in the multi-uprobe feature detector, from Andrii Nakryiko.

5) Revert support for redirect to any xsk socket bound to the same umem
   as it can result in corrupted ring state which can lead to a crash when
   flushing rings. A different approach will be pursued for bpf-next to
   address it safely, from Magnus Karlsson.

6) Fix inet_csk_accept prototype in test_sk_storage_tracing.c which caused
   BPF CI failure after the last tree fast forwarding, from Andrii Nakryiko.

7) Fix a coccicheck warning in BPF devmap that iterator variable cannot
   be NULL, from Thorsten Blum.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  Revert "xsk: Document ability to redirect to any socket bound to the same umem"
  Revert "xsk: Support redirect to any socket bound to the same umem"
  bpf: Set run context for rawtp test_run callback
  bpf: Fix a potential use-after-free in bpf_link_free()
  bpf, devmap: Remove unnecessary if check in for loop
  libbpf: don't close(-1) in multi-uprobe feature detector
  bpf: Fix bpf_session_cookie BTF_ID in special_kfunc_set list
  selftests/bpf: fix inet_csk_accept prototype in test_sk_storage_tracing.c
====================

Link: https://lore.kernel.org/r/20240605091525.22628-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 10 insertions, 10 deletions

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 4e2cdbb5629f..7f3b34452243 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -760,9 +760,6 @@ int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
 		for (i = 0; i < dtab->n_buckets; i++) {
 			head = dev_map_index_hash(dtab, i);
 			hlist_for_each_entry_safe(dst, next, head, index_hlist) {
-				if (!dst)
-					continue;
-
 				if (is_ifindex_excluded(excluded_devices, num_excluded,
 							dst->dev->ifindex))
 					continue;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2222c3ff88e7..f45ed6adc092 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2998,6 +2998,7 @@ static int bpf_obj_get(const union bpf_attr *attr)
 void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,
 		   const struct bpf_link_ops *ops, struct bpf_prog *prog)
 {
+	WARN_ON(ops->dealloc && ops->dealloc_deferred);
 	atomic64_set(&link->refcnt, 1);
 	link->type = type;
 	link->id = 0;
@@ -3056,16 +3057,17 @@ static void bpf_link_defer_dealloc_mult_rcu_gp(struct rcu_head *rcu)
 /* bpf_link_free is guaranteed to be called from process context */
 static void bpf_link_free(struct bpf_link *link)
 {
+	const struct bpf_link_ops *ops = link->ops;
 	bool sleepable = false;
 
 	bpf_link_free_id(link->id);
 	if (link->prog) {
 		sleepable = link->prog->sleepable;
 		/* detach BPF program, clean up used resources */
-		link->ops->release(link);
+		ops->release(link);
 		bpf_prog_put(link->prog);
 	}
-	if (link->ops->dealloc_deferred) {
+	if (ops->dealloc_deferred) {
 		/* schedule BPF link deallocation; if underlying BPF program
 		 * is sleepable, we need to first wait for RCU tasks trace
 		 * sync, then go through "classic" RCU grace period
@@ -3074,9 +3076,8 @@ static void bpf_link_free(struct bpf_link *link)
 			call_rcu_tasks_trace(&link->rcu, bpf_link_defer_dealloc_mult_rcu_gp);
 		else
 			call_rcu(&link->rcu, bpf_link_defer_dealloc_rcu_gp);
-	}
-	if (link->ops->dealloc)
-		link->ops->dealloc(link);
+	} else if (ops->dealloc)
+		ops->dealloc(link);
 }
 
 static void bpf_link_put_deferred(struct work_struct *work)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 48f3a9acdef3..36ef8e96787e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11128,7 +11128,11 @@ BTF_ID(func, bpf_iter_css_task_new)
 #else
 BTF_ID_UNUSED
 #endif
+#ifdef CONFIG_BPF_EVENTS
 BTF_ID(func, bpf_session_cookie)
+#else
+BTF_ID_UNUSED
+#endif
 
 static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
 {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 6249dac61701..d1daeab1bbc1 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3517,7 +3517,6 @@ static u64 bpf_uprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
 }
 #endif /* CONFIG_UPROBES */
 
-#ifdef CONFIG_FPROBE
 __bpf_kfunc_start_defs();
 
 __bpf_kfunc bool bpf_session_is_return(void)
@@ -3566,4 +3565,3 @@ static int __init bpf_kprobe_multi_kfuncs_init(void)
 }
 
 late_initcall(bpf_kprobe_multi_kfuncs_init);
-#endif