Merge 5.10.55 into android12-5.10-lts

Changes in 5.10.55
	tools: Allow proper CC/CXX/... override with LLVM=1 in Makefile.include
	io_uring: fix link timeout refs
	KVM: x86: determine if an exception has an error code only when injecting it.
	af_unix: fix garbage collect vs MSG_PEEK
	workqueue: fix UAF in pwq_unbound_release_workfn()
	cgroup1: fix leaked context root causing sporadic NULL deref in LTP
	net/802/mrp: fix memleak in mrp_request_join()
	net/802/garp: fix memleak in garp_request_join()
	net: annotate data race around sk_ll_usec
	sctp: move 198 addresses from unusable to private scope
	rcu-tasks: Don't delete holdouts within trc_inspect_reader()
	rcu-tasks: Don't delete holdouts within trc_wait_for_one_reader()
	ipv6: allocate enough headroom in ip6_finish_output2()
	drm/ttm: add a check against null pointer dereference
	hfs: add missing clean-up in hfs_fill_super
	hfs: fix high memory mapping in hfs_bnode_read
	hfs: add lock nesting notation to hfs_find_init
	firmware: arm_scmi: Fix possible scmi_linux_errmap buffer overflow
	firmware: arm_scmi: Fix range check for the maximum number of pending messages
	cifs: fix the out of range assignment to bit fields in parse_server_interfaces
	iomap: remove the length variable in iomap_seek_data
	iomap: remove the length variable in iomap_seek_hole
	ARM: dts: versatile: Fix up interrupt controller node names
	ipv6: ip6_finish_output2: set sk into newly allocated nskb
	Linux 5.10.55

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I2d673bdde784b3689af73289305091dbd4ead042

Makefile

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 VERSION = 5
 PATCHLEVEL = 10
-SUBLEVEL = 54
+SUBLEVEL = 55
 EXTRAVERSION =
 NAME = Dare mighty things
 

arch/arm/boot/dts/versatile-ab.dts

@@ -195,16 +195,15 @@
 		#size-cells = <1>;
 		ranges;
 
-		vic: intc@10140000 {
+		vic: interrupt-controller@10140000 {
 			compatible = "arm,versatile-vic";
 			interrupt-controller;
 			#interrupt-cells = <1>;
 			reg = <0x10140000 0x1000>;
-			clear-mask = <0xffffffff>;
 			valid-mask = <0xffffffff>;
 		};
 
-		sic: intc@10003000 {
+		sic: interrupt-controller@10003000 {
 			compatible = "arm,versatile-sic";
 			interrupt-controller;
 			#interrupt-cells = <1>;

arch/arm/boot/dts/versatile-pb.dts

@@ -7,7 +7,7 @@
 
 	amba {
 		/* The Versatile PB is using more SIC IRQ lines than the AB */
-		sic: intc@10003000 {
+		sic: interrupt-controller@10003000 {
 			clear-mask = <0xffffffff>;
 			/*
 			 * Valid interrupt lines mask according to

arch/x86/kvm/x86.c

@@ -541,8 +541,6 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
 
 	if (!vcpu->arch.exception.pending && !vcpu->arch.exception.injected) {
 	queue:
-		if (has_error && !is_protmode(vcpu))
-			has_error = false;
 		if (reinject) {
 			/*
 			 * On vmentry, vcpu->arch.exception.pending is only
@@ -8265,6 +8263,13 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu)
 	kvm_x86_ops.update_cr8_intercept(vcpu, tpr, max_irr);
 }
 
+static void kvm_inject_exception(struct kvm_vcpu *vcpu)
+{
+	if (vcpu->arch.exception.error_code && !is_protmode(vcpu))
+		vcpu->arch.exception.error_code = false;
+	kvm_x86_ops.queue_exception(vcpu);
+}
+
 static void inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
 {
 	int r;
@@ -8273,7 +8278,7 @@ static void inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit
 	/* try to reinject previous events if any */
 
 	if (vcpu->arch.exception.injected) {
-		kvm_x86_ops.queue_exception(vcpu);
+		kvm_inject_exception(vcpu);
 		can_inject = false;
 	}
 	/*
@@ -8336,7 +8341,7 @@ static void inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit
 			}
 		}
 
-		kvm_x86_ops.queue_exception(vcpu);
+		kvm_inject_exception(vcpu);
 		can_inject = false;
 	}
 

drivers/firmware/arm_scmi/driver.c

@@ -49,7 +49,6 @@ enum scmi_error_codes {
 	SCMI_ERR_GENERIC = -8,	/* Generic Error */
 	SCMI_ERR_HARDWARE = -9,	/* Hardware Error */
 	SCMI_ERR_PROTOCOL = -10,/* Protocol Error */
-	SCMI_ERR_MAX
 };
 
 /* List of all SCMI devices active in system */
@@ -168,8 +167,10 @@ static const int scmi_linux_errmap[] = {
 
 static inline int scmi_to_linux_errno(int errno)
 {
-	if (errno < SCMI_SUCCESS && errno > SCMI_ERR_MAX)
+	int err_idx = -errno;
-		return scmi_linux_errmap[-errno];
+
+	if (err_idx >= SCMI_SUCCESS && err_idx < ARRAY_SIZE(scmi_linux_errmap))
+		return scmi_linux_errmap[err_idx];
 	return -EIO;
 }
 
@@ -1029,8 +1030,9 @@ static int __scmi_xfer_info_init(struct scmi_info *sinfo,
 	const struct scmi_desc *desc = sinfo->desc;
 
 	/* Pre-allocated messages, no more than what hdr.seq can support */
-	if (WARN_ON(desc->max_msg >= MSG_TOKEN_MAX)) {
+	if (WARN_ON(!desc->max_msg || desc->max_msg > MSG_TOKEN_MAX)) {
-		dev_err(dev, "Maximum message of %d exceeds supported %ld\n",
+		dev_err(dev,
+			"Invalid maximum messages %d, not in range [1 - %lu]\n",
 			desc->max_msg, MSG_TOKEN_MAX);
 		return -EINVAL;
 	}

drivers/gpu/drm/ttm/ttm_range_manager.c

@@ -147,6 +147,9 @@ int ttm_range_man_fini(struct ttm_bo_device *bdev,
 	struct drm_mm *mm = &rman->mm;
 	int ret;
 
+	if (!man)
+		return 0;
+
 	ttm_resource_manager_set_used(man, false);
 
 	ret = ttm_resource_manager_force_list_clean(bdev, man);

fs/cifs/smb2ops.c

@@ -497,8 +497,8 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 	p = buf;
 	while (bytes_left >= sizeof(*p)) {
 		info->speed = le64_to_cpu(p->LinkSpeed);
-		info->rdma_capable = le32_to_cpu(p->Capability & RDMA_CAPABLE);
+		info->rdma_capable = le32_to_cpu(p->Capability & RDMA_CAPABLE) ? 1 : 0;
-		info->rss_capable = le32_to_cpu(p->Capability & RSS_CAPABLE);
+		info->rss_capable = le32_to_cpu(p->Capability & RSS_CAPABLE) ? 1 : 0;
 
 		cifs_dbg(FYI, "%s: adding iface %zu\n", __func__, *iface_count);
 		cifs_dbg(FYI, "%s: speed %zu bps\n", __func__, info->speed);

fs/hfs/bfind.c

@@ -25,7 +25,19 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
 	fd->key = ptr + tree->max_key_len + 2;
 	hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n",
 		tree->cnid, __builtin_return_address(0));
-	mutex_lock(&tree->tree_lock);
+	switch (tree->cnid) {
+	case HFS_CAT_CNID:
+		mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
+		break;
+	case HFS_EXT_CNID:
+		mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
+		break;
+	case HFS_ATTR_CNID:
+		mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
+		break;
+	default:
+		return -EINVAL;
+	}
 	return 0;
 }
 

fs/hfs/bnode.c

@@ -15,16 +15,31 @@
 
 #include "btree.h"
 
-void hfs_bnode_read(struct hfs_bnode *node, void *buf,
+void hfs_bnode_read(struct hfs_bnode *node, void *buf, int off, int len)
-		int off, int len)
 {
 	struct page *page;
+	int pagenum;
+	int bytes_read;
+	int bytes_to_read;
+	void *vaddr;
 
 	off += node->page_offset;
-	page = node->page[0];
+	pagenum = off >> PAGE_SHIFT;
+	off &= ~PAGE_MASK; /* compute page offset for the first page */
 
-	memcpy(buf, kmap(page) + off, len);
+	for (bytes_read = 0; bytes_read < len; bytes_read += bytes_to_read) {
-	kunmap(page);
+		if (pagenum >= node->tree->pages_per_bnode)
+			break;
+		page = node->page[pagenum];
+		bytes_to_read = min_t(int, len - bytes_read, PAGE_SIZE - off);
+
+		vaddr = kmap_atomic(page);
+		memcpy(buf + bytes_read, vaddr + off, bytes_to_read);
+		kunmap_atomic(vaddr);
+
+		pagenum++;
+		off = 0; /* page offset only applies to the first page */
+	}
 }
 
 u16 hfs_bnode_read_u16(struct hfs_bnode *node, int off)

fs/hfs/btree.h

@@ -13,6 +13,13 @@ typedef int (*btree_keycmp)(const btree_key *, const btree_key *);
 
 #define NODE_HASH_SIZE  256
 
+/* B-tree mutex nested subclasses */
+enum hfs_btree_mutex_classes {
+	CATALOG_BTREE_MUTEX,
+	EXTENTS_BTREE_MUTEX,
+	ATTR_BTREE_MUTEX,
+};
+
 /* A HFS BTree held in memory */
 struct hfs_btree {
 	struct super_block *sb;

fs/hfs/super.c

@@ -420,14 +420,12 @@ static int hfs_fill_super(struct super_block *sb, void *data, int silent)
 	if (!res) {
 		if (fd.entrylength > sizeof(rec) || fd.entrylength < 0) {
 			res =  -EIO;
-			goto bail;
+			goto bail_hfs_find;
 		}
 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
 	}
-	if (res) {
+	if (res)
-		hfs_find_exit(&fd);
+		goto bail_hfs_find;
-		goto bail_no_root;
-	}
 	res = -EINVAL;
 	root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
 	hfs_find_exit(&fd);
@@ -443,6 +441,8 @@ static int hfs_fill_super(struct super_block *sb, void *data, int silent)
 	/* everything's okay */
 	return 0;
 
+bail_hfs_find:
+	hfs_find_exit(&fd);
 bail_no_root:
 	pr_err("get root inode failed\n");
 bail:

fs/internal.h

@@ -64,7 +64,6 @@ extern void __init chrdev_init(void);
  */
 extern const struct fs_context_operations legacy_fs_context_ops;
 extern int parse_monolithic_mount_data(struct fs_context *, void *);
-extern void fc_drop_locked(struct fs_context *);
 extern void vfs_clean_context(struct fs_context *fc);
 extern int finish_clean_context(struct fs_context *fc);
 

fs/io_uring.c

@@ -6266,7 +6266,6 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
 	if (prev) {
 		io_async_find_and_cancel(ctx, req, prev->user_data, -ETIME);
 		io_put_req_deferred(prev, 1);
-		io_put_req_deferred(req, 1);
 	} else {
 		io_cqring_add_event(req, -ETIME, 0);
 		io_put_req_deferred(req, 1);

fs/iomap/seek.c

@@ -140,23 +140,20 @@ loff_t
 iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
 {
 	loff_t size = i_size_read(inode);
-	loff_t length = size - offset;
 	loff_t ret;
 
 	/* Nothing to be found before or beyond the end of the file. */
 	if (offset < 0 || offset >= size)
 		return -ENXIO;
 
-	while (length > 0) {
+	while (offset < size) {
-		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
+		ret = iomap_apply(inode, offset, size - offset, IOMAP_REPORT,
-				  &offset, iomap_seek_hole_actor);
+				  ops, &offset, iomap_seek_hole_actor);
 		if (ret < 0)
 			return ret;
 		if (ret == 0)
 			break;
-
 		offset += ret;
-		length -= ret;
 	}
 
 	return offset;
@@ -186,27 +183,23 @@ loff_t
 iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
 {
 	loff_t size = i_size_read(inode);
-	loff_t length = size - offset;
 	loff_t ret;
 
 	/* Nothing to be found before or beyond the end of the file. */
 	if (offset < 0 || offset >= size)
 		return -ENXIO;
 
-	while (length > 0) {
+	while (offset < size) {
-		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
+		ret = iomap_apply(inode, offset, size - offset, IOMAP_REPORT,
-				  &offset, iomap_seek_data_actor);
+				  ops, &offset, iomap_seek_data_actor);
 		if (ret < 0)
 			return ret;
 		if (ret == 0)
-			break;
+			return offset;
-
 		offset += ret;
-		length -= ret;
 	}
 
-	if (length <= 0)
+	/* We've reached the end of the file without finding data */
-		return -ENXIO;
+	return -ENXIO;
-	return offset;
 }
 EXPORT_SYMBOL_GPL(iomap_seek_data);

include/linux/fs_context.h

@@ -139,6 +139,7 @@ extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
 extern int generic_parse_monolithic(struct fs_context *fc, void *data);
 extern int vfs_get_tree(struct fs_context *fc);
 extern void put_fs_context(struct fs_context *fc);
+extern void fc_drop_locked(struct fs_context *fc);
 
 /*
  * sget() wrappers to be called from the ->get_tree() op.

include/net/busy_poll.h

@@ -36,7 +36,7 @@ static inline bool net_busy_loop_on(void)
 
 static inline bool sk_can_busy_loop(const struct sock *sk)
 {
-	return sk->sk_ll_usec && !signal_pending(current);
+	return READ_ONCE(sk->sk_ll_usec) && !signal_pending(current);
 }
 
 bool sk_busy_loop_end(void *p, unsigned long start_time);

include/net/sctp/constants.h

@@ -340,8 +340,7 @@ enum {
 #define SCTP_SCOPE_POLICY_MAX	SCTP_SCOPE_POLICY_LINK
 
 /* Based on IPv4 scoping <draft-stewart-tsvwg-sctp-ipv4-00.txt>,
- * SCTP IPv4 unusable addresses: 0.0.0.0/8, 224.0.0.0/4, 198.18.0.0/24,
+ * SCTP IPv4 unusable addresses: 0.0.0.0/8, 224.0.0.0/4, 192.88.99.0/24.
- * 192.88.99.0/24.
  * Also, RFC 8.4, non-unicast addresses are not considered valid SCTP
  * addresses.
  */
@@ -349,7 +348,6 @@ enum {
 	((htonl(INADDR_BROADCAST) == a) ||  \
 	 ipv4_is_multicast(a) ||	    \
 	 ipv4_is_zeronet(a) ||		    \
-	 ipv4_is_test_198(a) ||		    \
 	 ipv4_is_anycast_6to4(a))
 
 /* Flags used for the bind address copy functions.  */

kernel/cgroup/cgroup-v1.c

@@ -1228,9 +1228,7 @@ int cgroup1_get_tree(struct fs_context *fc)
 		ret = cgroup_do_get_tree(fc);
 
 	if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) {
-		struct super_block *sb = fc->root->d_sb;
+		fc_drop_locked(fc);
-		dput(fc->root);
-		deactivate_locked_super(sb);
 		ret = 1;
 	}
 

kernel/rcu/tasks.h

@@ -879,10 +879,9 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg)
 		in_qs = likely(!t->trc_reader_nesting);
 	}
 
-	// Mark as checked.  Because this is called from the grace-period
+	// Mark as checked so that the grace-period kthread will
-	// kthread, also remove the task from the holdout list.
+	// remove it from the holdout list.
 	t->trc_reader_checked = true;
-	trc_del_holdout(t);
 
 	if (in_qs)
 		return true;  // Already in quiescent state, done!!!
@@ -909,7 +908,6 @@ static void trc_wait_for_one_reader(struct task_struct *t,
 	// The current task had better be in a quiescent state.
 	if (t == current) {
 		t->trc_reader_checked = true;
-		trc_del_holdout(t);
 		WARN_ON_ONCE(t->trc_reader_nesting);
 		return;
 	}

kernel/workqueue.c

@@ -3689,15 +3689,21 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
 						  unbound_release_work);
 	struct workqueue_struct *wq = pwq->wq;
 	struct worker_pool *pool = pwq->pool;
-	bool is_last;
+	bool is_last = false;
 
-	if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
+	/*
-		return;
+	 * when @pwq is not linked, it doesn't hold any reference to the
+	 * @wq, and @wq is invalid to access.
+	 */
+	if (!list_empty(&pwq->pwqs_node)) {
+		if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
+			return;
 
-	mutex_lock(&wq->mutex);
+		mutex_lock(&wq->mutex);
-	list_del_rcu(&pwq->pwqs_node);
+		list_del_rcu(&pwq->pwqs_node);
-	is_last = list_empty(&wq->pwqs);
+		is_last = list_empty(&wq->pwqs);
-	mutex_unlock(&wq->mutex);
+		mutex_unlock(&wq->mutex);
+	}
 
 	mutex_lock(&wq_pool_mutex);
 	put_unbound_pool(pool);

net/802/garp.c

@@ -203,6 +203,19 @@ static void garp_attr_destroy(struct garp_applicant *app, struct garp_attr *attr
 	kfree(attr);
 }
 
+static void garp_attr_destroy_all(struct garp_applicant *app)
+{
+	struct rb_node *node, *next;
+	struct garp_attr *attr;
+
+	for (node = rb_first(&app->gid);
+	     next = node ? rb_next(node) : NULL, node != NULL;
+	     node = next) {
+		attr = rb_entry(node, struct garp_attr, node);
+		garp_attr_destroy(app, attr);
+	}
+}
+
 static int garp_pdu_init(struct garp_applicant *app)
 {
 	struct sk_buff *skb;
@@ -609,6 +622,7 @@ void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl
 
 	spin_lock_bh(&app->lock);
 	garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
+	garp_attr_destroy_all(app);
 	garp_pdu_queue(app);
 	spin_unlock_bh(&app->lock);
 

net/802/mrp.c

@@ -292,6 +292,19 @@ static void mrp_attr_destroy(struct mrp_applicant *app, struct mrp_attr *attr)
 	kfree(attr);
 }
 
+static void mrp_attr_destroy_all(struct mrp_applicant *app)
+{
+	struct rb_node *node, *next;
+	struct mrp_attr *attr;
+
+	for (node = rb_first(&app->mad);
+	     next = node ? rb_next(node) : NULL, node != NULL;
+	     node = next) {
+		attr = rb_entry(node, struct mrp_attr, node);
+		mrp_attr_destroy(app, attr);
+	}
+}
+
 static int mrp_pdu_init(struct mrp_applicant *app)
 {
 	struct sk_buff *skb;
@@ -895,6 +908,7 @@ void mrp_uninit_applicant(struct net_device *dev, struct mrp_application *appl)
 
 	spin_lock_bh(&app->lock);
 	mrp_mad_event(app, MRP_EVENT_TX);
+	mrp_attr_destroy_all(app);
 	mrp_pdu_queue(app);
 	spin_unlock_bh(&app->lock);
 

net/core/sock.c

@@ -1166,7 +1166,7 @@ set_sndbuf:
 			if (val < 0)
 				ret = -EINVAL;
 			else
-				sk->sk_ll_usec = val;
+				WRITE_ONCE(sk->sk_ll_usec, val);
 		}
 		break;
 #endif

net/ipv6/ip6_output.c

@@ -60,10 +60,38 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct net_device *dev = dst->dev;
+	unsigned int hh_len = LL_RESERVED_SPACE(dev);
+	int delta = hh_len - skb_headroom(skb);
 	const struct in6_addr *nexthop;
 	struct neighbour *neigh;
 	int ret;
 
+	/* Be paranoid, rather than too clever. */
+	if (unlikely(delta > 0) && dev->header_ops) {
+		/* pskb_expand_head() might crash, if skb is shared */
+		if (skb_shared(skb)) {
+			struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
+			if (likely(nskb)) {
+				if (skb->sk)
+					skb_set_owner_w(nskb, skb->sk);
+				consume_skb(skb);
+			} else {
+				kfree_skb(skb);
+			}
+			skb = nskb;
+		}
+		if (skb &&
+		    pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
+			kfree_skb(skb);
+			skb = NULL;
+		}
+		if (!skb) {
+			IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
+			return -ENOMEM;
+		}
+	}
+
 	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
 		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
 

net/sctp/protocol.c

@@ -397,7 +397,8 @@ static enum sctp_scope sctp_v4_scope(union sctp_addr *addr)
 		retval = SCTP_SCOPE_LINK;
 	} else if (ipv4_is_private_10(addr->v4.sin_addr.s_addr) ||
 		   ipv4_is_private_172(addr->v4.sin_addr.s_addr) ||
-		   ipv4_is_private_192(addr->v4.sin_addr.s_addr)) {
+		   ipv4_is_private_192(addr->v4.sin_addr.s_addr) ||
+		   ipv4_is_test_198(addr->v4.sin_addr.s_addr)) {
 		retval = SCTP_SCOPE_PRIVATE;
 	} else {
 		retval = SCTP_SCOPE_GLOBAL;

net/unix/af_unix.c

@@ -1521,6 +1521,53 @@ out:
 	return err;
 }
 
+static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
+{
+	scm->fp = scm_fp_dup(UNIXCB(skb).fp);
+
+	/*
+	 * Garbage collection of unix sockets starts by selecting a set of
+	 * candidate sockets which have reference only from being in flight
+	 * (total_refs == inflight_refs).  This condition is checked once during
+	 * the candidate collection phase, and candidates are marked as such, so
+	 * that non-candidates can later be ignored.  While inflight_refs is
+	 * protected by unix_gc_lock, total_refs (file count) is not, hence this
+	 * is an instantaneous decision.
+	 *
+	 * Once a candidate, however, the socket must not be reinstalled into a
+	 * file descriptor while the garbage collection is in progress.
+	 *
+	 * If the above conditions are met, then the directed graph of
+	 * candidates (*) does not change while unix_gc_lock is held.
+	 *
+	 * Any operations that changes the file count through file descriptors
+	 * (dup, close, sendmsg) does not change the graph since candidates are
+	 * not installed in fds.
+	 *
+	 * Dequeing a candidate via recvmsg would install it into an fd, but
+	 * that takes unix_gc_lock to decrement the inflight count, so it's
+	 * serialized with garbage collection.
+	 *
+	 * MSG_PEEK is special in that it does not change the inflight count,
+	 * yet does install the socket into an fd.  The following lock/unlock
+	 * pair is to ensure serialization with garbage collection.  It must be
+	 * done between incrementing the file count and installing the file into
+	 * an fd.
+	 *
+	 * If garbage collection starts after the barrier provided by the
+	 * lock/unlock, then it will see the elevated refcount and not mark this
+	 * as a candidate.  If a garbage collection is already in progress
+	 * before the file count was incremented, then the lock/unlock pair will
+	 * ensure that garbage collection is finished before progressing to
+	 * installing the fd.
+	 *
+	 * (*) A -> B where B is on the queue of A or B is on the queue of C
+	 * which is on the queue of listening socket A.
+	 */
+	spin_lock(&unix_gc_lock);
+	spin_unlock(&unix_gc_lock);
+}
+
 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
 {
 	int err = 0;
@@ -2170,7 +2217,7 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 		sk_peek_offset_fwd(sk, size);
 
 		if (UNIXCB(skb).fp)
-			scm.fp = scm_fp_dup(UNIXCB(skb).fp);
+			unix_peek_fds(&scm, skb);
 	}
 	err = (flags & MSG_TRUNC) ? skb->len - skip : size;
 
@@ -2413,7 +2460,7 @@ unlock:
 			/* It is questionable, see note in unix_dgram_recvmsg.
 			 */
 			if (UNIXCB(skb).fp)
-				scm.fp = scm_fp_dup(UNIXCB(skb).fp);
+				unix_peek_fds(&scm, skb);
 
 			sk_peek_offset_fwd(sk, chunk);
 

tools/scripts/Makefile.include

@@ -39,8 +39,6 @@ EXTRA_WARNINGS += -Wundef
 EXTRA_WARNINGS += -Wwrite-strings
 EXTRA_WARNINGS += -Wformat
 
-CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
-
 # Makefiles suck: This macro sets a default value of $(2) for the
 # variable named by $(1), unless the variable has been set by
 # environment or command line. This is necessary for CC and AR
@@ -52,12 +50,22 @@ define allow-override
     $(eval $(1) = $(2)))
 endef
 
+ifneq ($(LLVM),)
+$(call allow-override,CC,clang)
+$(call allow-override,AR,llvm-ar)
+$(call allow-override,LD,ld.lld)
+$(call allow-override,CXX,clang++)
+$(call allow-override,STRIP,llvm-strip)
+else
 # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
 $(call allow-override,AR,$(CROSS_COMPILE)ar)
 $(call allow-override,LD,$(CROSS_COMPILE)ld)
 $(call allow-override,CXX,$(CROSS_COMPILE)g++)
 $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
+endif
+
+CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
 
 ifneq ($(LLVM),)
 HOSTAR  ?= llvm-ar