From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Since Clang generates a wrong DWARF5 format, dwarf_decl_file() can
return NULL. In that case the perf probe will crash by SIGSEGV.
This adds checks of the return value of dwarf_decl_file() to avoid
such SEGV on a broken DWARF file.
Without this, perf probe crashes like below;
$ ./perf probe -k $BIN_PATH/vmlinux -s $SRC_PATH -L vfs_read:10
Segmentation fault
With this, perf probe just warns it;
$ ./perf probe -k $BIN_PATH/vmlinux -s $SRC_PATH -L vfs_read:10
Debuginfo analysis failed.
Error: Failed to show lines.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
tools/perf/util/dwarf-aux.c | 7 ++++++-
tools/perf/util/probe-finder.c | 29 +++++++++++++++++++++--------
2 files changed, 27 insertions(+), 9 deletions(-)
@@ -137,7 +137,7 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr,
}
out:
- return *lineno ?: -ENOENT;
+ return (*lineno && *fname) ? *lineno : -ENOENT;
}
static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data);
@@ -874,6 +874,11 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
dwarf_decl_line(rt_die, &decl);
decf = dwarf_decl_file(rt_die);
+ if (!decf) {
+ pr_debug2("Failed to get the declared file name of %s\n",
+ dwarf_diename(rt_die));
+ return -EINVAL;
+ }
} else
cu_die = rt_die;
if (!cu_die) {
@@ -1063,6 +1063,7 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
struct dwarf_callback_param *param = data;
struct probe_finder *pf = param->data;
struct perf_probe_point *pp = &pf->pev->point;
+ const char *fname;
/* Check tag and diename */
if (!die_is_func_def(sp_die) ||
@@ -1070,12 +1071,17 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
return DWARF_CB_OK;
/* Check declared file */
- if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
+ fname = dwarf_decl_file(sp_die);
+ if (!fname) {
+ pr_warning("A function DIE doesn't have decl_line. Maybe broken DWARF?\n");
+ return DWARF_CB_OK;
+ }
+ if (pp->file && fname && strtailcmp(pp->file, fname))
return DWARF_CB_OK;
pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
(unsigned long)dwarf_dieoffset(sp_die));
- pf->fname = dwarf_decl_file(sp_die);
+ pf->fname = fname;
if (pp->line) { /* Function relative line */
dwarf_decl_line(sp_die, &pf->lno);
pf->lno += pp->line;
@@ -1134,6 +1140,7 @@ struct pubname_callback_param {
static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
{
struct pubname_callback_param *param = data;
+ const char *fname;
if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
@@ -1143,9 +1150,11 @@ static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
return DWARF_CB_OK;
- if (param->file &&
- strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
- return DWARF_CB_OK;
+ if (param->file) {
+ fname = dwarf_decl_file(param->sp_die);
+ if (!fname || strtailcmp(param->file, fname))
+ return DWARF_CB_OK;
+ }
param->found = 1;
return DWARF_CB_ABORT;
@@ -1779,7 +1788,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, u64 addr,
}
/* Verify the lineno and baseline are in a same file */
tmp = dwarf_decl_file(&spdie);
- if (!tmp || strcmp(tmp, fname) != 0)
+ if (!tmp || (fname && strcmp(tmp, fname) != 0))
lineno = 0;
}
@@ -1889,10 +1898,14 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
struct dwarf_callback_param *param = data;
struct line_finder *lf = param->data;
struct line_range *lr = lf->lr;
+ const char *fname;
/* Check declared file */
- if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
- return DWARF_CB_OK;
+ if (lr->file) {
+ fname = dwarf_decl_file(sp_die);
+ if (!fname || strtailcmp(lr->file, fname))
+ return DWARF_CB_OK;
+ }
if (die_match_name(sp_die, lr->function) && die_is_func_def(sp_die)) {
lf->fname = dwarf_decl_file(sp_die);