4 files changed, 26 insertions, 12 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 752b5d265..4f2513388 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3234,13 +3234,10 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
 	di_args->bytes_used = btrfs_device_get_bytes_used(dev);
 	di_args->total_bytes = btrfs_device_get_total_bytes(dev);
 	memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
-	if (dev->name) {
-		strncpy(di_args->path, rcu_str_deref(dev->name),
-				sizeof(di_args->path) - 1);
-		di_args->path[sizeof(di_args->path) - 1] = 0;
-	} else {
+	if (dev->name)
+		strscpy(di_args->path, rcu_str_deref(dev->name), sizeof(di_args->path));
+	else
 		di_args->path[0] = '\0';
-	}
 
 out:
 	rcu_read_unlock();
diff --git a/fs/btrfs/rcu-string.h b/fs/btrfs/rcu-string.h
index a97dc74a4..02f15321c 100644
--- a/fs/btrfs/rcu-string.h
+++ b/fs/btrfs/rcu-string.h
@@ -18,7 +18,11 @@ static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask)
 					 (len * sizeof(char)), mask);
 	if (!ret)
 		return ret;
-	strncpy(ret->str, src, len);
+	/* Warn if the source got unexpectedly truncated. */
+	if (WARN_ON(strscpy(ret->str, src, len) < 0)) {
+		kfree(ret);
+		return NULL;
+	}
 	return ret;
 }
 
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index eb2f8e84f..1f535cd99 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1306,6 +1306,7 @@ static int find_extent_clone(struct send_ctx *sctx,
 	u64 disk_byte;
 	u64 num_bytes;
 	u64 extent_item_pos;
+	u64 extent_refs;
 	u64 flags = 0;
 	struct btrfs_file_extent_item *fi;
 	struct extent_buffer *eb = path->nodes[0];
@@ -1373,14 +1374,22 @@ static int find_extent_clone(struct send_ctx *sctx,
 
 	ei = btrfs_item_ptr(tmp_path->nodes[0], tmp_path->slots[0],
 			    struct btrfs_extent_item);
+	extent_refs = btrfs_extent_refs(tmp_path->nodes[0], ei);
 	/*
 	 * Backreference walking (iterate_extent_inodes() below) is currently
 	 * too expensive when an extent has a large number of references, both
 	 * in time spent and used memory. So for now just fallback to write
 	 * operations instead of clone operations when an extent has more than
 	 * a certain amount of references.
+	 *
+	 * Also, if we have only one reference and only the send root as a clone
+	 * source - meaning no clone roots were given in the struct
+	 * btrfs_ioctl_send_args passed to the send ioctl - then it's our
+	 * reference and there's no point in doing backref walking which is
+	 * expensive, so exit early.
 	 */
-	if (btrfs_extent_refs(tmp_path->nodes[0], ei) > SEND_MAX_EXTENT_REFS) {
+	if ((extent_refs == 1 && sctx->clone_roots_cnt == 1) ||
+	    extent_refs > SEND_MAX_EXTENT_REFS) {
 		ret = -ENOENT;
 		goto out;
 	}
@@ -6817,10 +6826,10 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 	/*
 	 * Check that we don't overflow at later allocations, we request
 	 * clone_sources_count + 1 items, and compare to unsigned long inside
-	 * access_ok.
+	 * access_ok. Also set an upper limit for allocation size so this can't
+	 * easily exhaust memory. Max number of clone sources is about 200K.
 	 */
-	if (arg->clone_sources_count >
-	    ULONG_MAX / sizeof(struct clone_root) - 1) {
+	if (arg->clone_sources_count > SZ_8M / sizeof(struct clone_root)) {
 		ret = -EINVAL;
 		goto out;
 	}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2b4d33b58..0294f519c 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1418,7 +1418,7 @@ again:
 			goto out;
 	}
 
-	while (1) {
+	while (search_start < search_end) {
 		l = path->nodes[0];
 		slot = path->slots[0];
 		if (slot >= btrfs_header_nritems(l)) {
@@ -1441,6 +1441,9 @@ again:
 		if (key.type != BTRFS_DEV_EXTENT_KEY)
 			goto next;
 
+		if (key.offset > search_end)
+			break;
+
 		if (key.offset > search_start) {
 			hole_size = key.offset - search_start;
 
@@ -1515,6 +1518,7 @@ next:
 	else
 		ret = 0;
 
+	ASSERT(max_hole_start + max_hole_size <= search_end);
 out:
 	btrfs_free_path(path);
 	*start = max_hole_start;