Adding upstream version 4.19.282.upstream/4.19.282

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 13 insertions, 4 deletions

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;
 	}