Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Pull bpf fixes from Alexei Starovoitov:

 - Fix use-after-free in libbpf when map is resized (Adin Scannell)

 - Fix verifier assumptions about 2nd argument of bpf_sysctl_get_name
   (Jerome Marchand)

 - Fix verifier assumption of nullness of d_inode in dentry (Song Liu)

 - Fix global starvation of LRU map (Willem de Bruijn)

 - Fix potential NULL dereference in btf_dump__free (Yuan Chen)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  selftests/bpf: adapt one more case in test_lru_map to the new target_free
  libbpf: Fix possible use-after-free for externs
  selftests/bpf: Convert test_sysctl to prog_tests
  bpf: Specify access type of bpf_sysctl_get_name args
  libbpf: Fix null pointer dereference in btf_dump__free on allocation failure
  bpf: Adjust free target to avoid global starvation of LRU map
  bpf: Mark dentry->d_inode as trusted_or_null

4 files changed, 10 insertions, 7 deletions

diff --git a/kernel/bpf/bpf_lru_list.c b/kernel/bpf/bpf_lru_list.c
index 3dabdd137d10..2d6e1c98d8ad 100644
--- a/kernel/bpf/bpf_lru_list.c
+++ b/kernel/bpf/bpf_lru_list.c
@@ -337,12 +337,12 @@ static void bpf_lru_list_pop_free_to_local(struct bpf_lru *lru,
 				 list) {
 		__bpf_lru_node_move_to_free(l, node, local_free_list(loc_l),
 					    BPF_LRU_LOCAL_LIST_T_FREE);
-		if (++nfree == LOCAL_FREE_TARGET)
+		if (++nfree == lru->target_free)
 			break;
 	}
 
-	if (nfree < LOCAL_FREE_TARGET)
-		__bpf_lru_list_shrink(lru, l, LOCAL_FREE_TARGET - nfree,
+	if (nfree < lru->target_free)
+		__bpf_lru_list_shrink(lru, l, lru->target_free - nfree,
 				      local_free_list(loc_l),
 				      BPF_LRU_LOCAL_LIST_T_FREE);
 
@@ -577,6 +577,9 @@ static void bpf_common_lru_populate(struct bpf_lru *lru, void *buf,
 		list_add(&node->list, &l->lists[BPF_LRU_LIST_T_FREE]);
 		buf += elem_size;
 	}
+
+	lru->target_free = clamp((nr_elems / num_possible_cpus()) / 2,
+				 1, LOCAL_FREE_TARGET);
 }
 
 static void bpf_percpu_lru_populate(struct bpf_lru *lru, void *buf,
diff --git a/kernel/bpf/bpf_lru_list.h b/kernel/bpf/bpf_lru_list.h
index cbd8d3720c2b..fe2661a58ea9 100644
--- a/kernel/bpf/bpf_lru_list.h
+++ b/kernel/bpf/bpf_lru_list.h
@@ -58,6 +58,7 @@ struct bpf_lru {
 	del_from_htab_func del_from_htab;
 	void *del_arg;
 	unsigned int hash_offset;
+	unsigned int target_free;
 	unsigned int nr_scans;
 	bool percpu;
 };
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 9122c39870bf..f4885514f007 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -2134,7 +2134,7 @@ static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_WRITE,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a7d6e0c5928b..169845710c7e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7027,8 +7027,7 @@ BTF_TYPE_SAFE_TRUSTED(struct file) {
 	struct inode *f_inode;
 };
 
-BTF_TYPE_SAFE_TRUSTED(struct dentry) {
-	/* no negative dentry-s in places where bpf can see it */
+BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry) {
 	struct inode *d_inode;
 };
 
@@ -7066,7 +7065,6 @@ static bool type_is_trusted(struct bpf_verifier_env *env,
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));
-	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry));
 
 	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
 }
@@ -7076,6 +7074,7 @@ static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
 				    const char *field_name, u32 btf_id)
 {
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));
+	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry));
 
 	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
 					  "__safe_trusted_or_null");