Em Tue, Oct 12, 2021 at 04:25:21AM +0200, Ilya Leoshkevich escreveu:
> Variables can be allocated with or without specification, however,
> tag__recode_dwarf_type() always tries accessing it, leading to heap
> read overflows and subsequent logic bugs.
>
> Fix by introducing a bit that tracks whether or not specification is
> present.
Thanks, applied.
- Arnaldo
> Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
> ---
> dwarf_loader.c | 15 ++++++++++-----
> dwarves.h | 1 +
> 2 files changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/dwarf_loader.c b/dwarf_loader.c
> index 48e1bf0..60bdca3 100644
> --- a/dwarf_loader.c
> +++ b/dwarf_loader.c
> @@ -723,6 +723,7 @@ static struct variable *variable__new(Dwarf_Die *die, struct cu *cu, struct conf
> var->external = dwarf_hasattr(die, DW_AT_external);
> /* non-defining declaration of an object */
> var->declaration = dwarf_hasattr(die, DW_AT_declaration);
> + var->has_specification = has_specification;
> var->scope = VSCOPE_UNKNOWN;
> INIT_LIST_HEAD(&var->annots);
> var->ip.addr = 0;
> @@ -2291,12 +2292,16 @@ static int tag__recode_dwarf_type(struct tag *tag, struct cu *cu)
> goto find_type;
> case DW_TAG_variable: {
> struct variable *var = tag__variable(tag);
> - dwarf_off_ref specification = dwarf_tag__spec(dtag);
>
> - if (specification.off) {
> - dtype = dwarf_cu__find_tag_by_ref(cu->priv, &specification);
> - if (dtype)
> - var->spec = tag__variable(dtype->tag);
> + if (var->has_specification) {
> + dwarf_off_ref specification = dwarf_tag__spec(dtag);
> +
> + if (specification.off) {
> + dtype = dwarf_cu__find_tag_by_ref(cu->priv,
> + &specification);
> + if (dtype)
> + var->spec = tag__variable(dtype->tag);
> + }
> }
> }
>
> diff --git a/dwarves.h b/dwarves.h
> index 30d33fa..20608dd 100644
> --- a/dwarves.h
> +++ b/dwarves.h
> @@ -691,6 +691,7 @@ struct variable {
> const char *name;
> uint8_t external:1;
> uint8_t declaration:1;
> + uint8_t has_specification:1;
> enum vscope scope;
> struct location location;
> struct hlist_node tool_hnode;
> --
> 2.31.1
--
- Arnaldo
