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dwarf_loader: Fix heap overflow when accessing variable specification 

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.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ilya Leoshkevich 2021-10-12 04:25:21 +02:00 committed by Arnaldo Carvalho de Melo
parent a9c99e9881
commit 3cde0135ca
2 changed files with 11 additions and 5 deletions
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15
dwarf_loader.c
View File

@ -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);
}
}
}

1
dwarves.h
View File

@ -693,6 +693,7 @@ 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;