[PATCH v3 2/6] perf dwarf-aux: Fix libdw API contract violations

Ian Rogers
2026-05-03T00:36:01Z

Check return values of `dwarf_decl_line`, `dwarf_getfuncs`, and
`dwarf_lineaddr` to prevent using uninitialized stack variables or
incorrectly reporting success on failure.

Fixes: 57f95bf5f882 ("perf probe: Show correct statement line number by perf probe -l")
Fixes: 3f4460a28fb2 ("perf probe: Filter out redundant inline-instances")
Fixes: 75186a9b09e4 ("perf probe: Fix to show lines of sys_ functions correctly")
Fixes: e0d153c69040 ("perf-probe: Move dwarf library routines to dwarf-aux.{c, h}")
Fixes: 6243b9dc4c99 ("perf probe: Move dwarf specific functions to dwarf-aux.c")
Assisted-by: Gemini-CLI:Google Gemini 3
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/dwarf-aux.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 8e83cb2d565e..1168e69a9292 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -125,7 +125,8 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr,
&& die_entrypc(&die_mem, &faddr) == 0 &&
faddr == addr) {
*fname = die_get_decl_file(&die_mem);
- dwarf_decl_line(&die_mem, lineno);
+ if (dwarf_decl_line(&die_mem, lineno) != 0)
+ return -ENOENT;
goto out;
}

@@ -796,8 +797,7 @@ static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)

/* Ignore redundant instances */
if (dwarf_tag(inst) == DW_TAG_inlined_subroutine) {
- dwarf_decl_line(origin, &tmp);
- if (die_get_call_lineno(inst) == tmp) {
+ if (dwarf_decl_line(origin, &tmp) == 0 && die_get_call_lineno(inst) == tmp) {
tmp = die_get_decl_fileno(origin);
if (die_get_call_fileno(inst) == tmp)
return DIE_FIND_CB_CONTINUE;
@@ -949,7 +949,11 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
/* Get the CU die */
if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
- dwarf_decl_line(rt_die, &decl);
+ if (dwarf_decl_line(rt_die, &decl) != 0) {
+ pr_debug2("Failed to get the declared line number of %s\n",
+ dwarf_diename(rt_die));
+ return -EINVAL;
+ }
decf = die_get_decl_file(rt_die);
if (!decf) {
pr_debug2("Failed to get the declared file name of %s\n",
@@ -1003,8 +1007,7 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
die_get_call_lineno(&die_mem) == lineno)
goto found;

- dwarf_decl_line(&die_mem, &inl);
- if (inl != decl ||
+ if (dwarf_decl_line(&die_mem, &inl) != 0 || inl != decl ||
decf != die_get_decl_file(&die_mem))
continue;
}
@@ -1035,8 +1038,10 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
.data = data,
.retval = 0,
};
- dwarf_getfuncs(cu_die, __die_walk_culines_cb, &param, 0);
- ret = param.retval;
+ if (dwarf_getfuncs(cu_die, __die_walk_culines_cb, &param, 0) < 0)
+ ret = -EINVAL;
+ else
+ ret = param.retval;
}

return ret;
@@ -1940,10 +1945,12 @@ static bool die_get_postprologue_addr(unsigned long entrypc_idx,
break;
}

- dwarf_lineaddr(line, postprologue_addr);
- if (*postprologue_addr >= highpc)
- dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
- postprologue_addr);
+ if (dwarf_lineaddr(line, postprologue_addr) != 0)
+ return false;
+ if (*postprologue_addr >= highpc) {
+ if (dwarf_lineaddr(dwarf_onesrcline(lines, i - 1), postprologue_addr) != 0)
+ return false;
+ }

return true;
}
--
2.54.0.545.g6539524ca2-goog