zstreamdump dumps core printing truncated nvlist

This change prevents zstreamdump from crashing when trying to print
invalid nvlist data (DRR_BEGIN record) from a truncated send stream.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: loli10K <[email protected]>
Closes #7917 

1 files changed, 5 insertions, 3 deletions

diff --git a/cmd/zstreamdump/zstreamdump.c b/cmd/zstreamdump/zstreamdump.c
index 6c7150b10..a2edefa92 100644
--- a/cmd/zstreamdump/zstreamdump.c
+++ b/cmd/zstreamdump/zstreamdump.c
@@ -384,10 +384,12 @@ main(int argc, char *argv[])
 				if (ferror(send_stream))
 					perror("fread");
 				err = nvlist_unpack(buf, sz, &nv, 0);
-				if (err)
+				if (err) {
 					perror(strerror(err));
-				nvlist_print(stdout, nv);
-				nvlist_free(nv);
+				} else {
+					nvlist_print(stdout, nv);
+					nvlist_free(nv);
+				}
 			}
 			break;