libctf: create: don't add forwards if the type added already exists

This is what ctf_add_forward is documented to do, but it's not what it
actually does: the code is quite happy to add forwards that duplicate
existing structs, etc.

This is obviously wrong and breaks both the nondeduplicating linker
and the upcoming deduplicator, as well as allowing ordinary callers of
ctf_add_type to corrupt the dictionary by just adding the same root-
visible forward more than once.

libctf/
	* ctf-create.c (ctf_add_forward): Don't add forwards to
	types that already exist.
This commit is contained in:
Nick Alcock
2019-10-21 11:33:19 +01:00
parent fe4c2d5563
commit 6bbf9da892
2 changed files with 9 additions and 1 deletions

View File

@ -1229,7 +1229,10 @@ ctf_add_forward (ctf_file_t *fp, uint32_t flag, const char *name,
if (name != NULL)
type = ctf_lookup_by_rawname (fp, kind, name);
if ((type = ctf_add_generic (fp, flag, name, CTF_K_FORWARD,&dtd)) == CTF_ERR)
if (type)
return type;
if ((type = ctf_add_generic (fp, flag, name, CTF_K_FORWARD, &dtd)) == CTF_ERR)
return CTF_ERR; /* errno is set for us. */
dtd->dtd_data.ctt_info = CTF_TYPE_INFO (CTF_K_FORWARD, flag, 0);