From 7099153e8d7d0ed228c3a63cb06912c13c1082e5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= Date: Sun, 1 Oct 2017 16:45:13 +0200 Subject: [PATCH] tag: avoid NULL pointer arithmetic lookup_blob() etc. can return NULL if the referenced object isn't of the expected type. In theory it's wrong to reference the object member in that case. In practice it's OK because it's located at offset 0 for all types, so the pointer arithmetic (NULL + 0) is optimized out by the compiler. The issue is reported by Clang's AddressSanitizer, though. Avoid the ASan error by casting the results of the lookup functions to struct object pointers. That works fine with NULL pointers as well. We already rely on the object member being first in all object types in other places in the code. Signed-off-by: Rene Scharfe Signed-off-by: Junio C Hamano --- tag.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tag.c b/tag.c index 47f60ae151..a3ffffdbfa 100644 --- a/tag.c +++ b/tag.c @@ -142,13 +142,13 @@ int parse_tag_buffer(struct tag *item, const void *data, unsigned long size) bufptr = nl + 1; if (!strcmp(type, blob_type)) { - item->tagged = &lookup_blob(&oid)->object; + item->tagged = (struct object *)lookup_blob(&oid); } else if (!strcmp(type, tree_type)) { - item->tagged = &lookup_tree(&oid)->object; + item->tagged = (struct object *)lookup_tree(&oid); } else if (!strcmp(type, commit_type)) { - item->tagged = &lookup_commit(&oid)->object; + item->tagged = (struct object *)lookup_commit(&oid); } else if (!strcmp(type, tag_type)) { - item->tagged = &lookup_tag(&oid)->object; + item->tagged = (struct object *)lookup_tag(&oid); } else { error("Unknown type %s", type); item->tagged = NULL;