From 98e4c68ddcaf3721df9bef809775a8e3562cb6f9 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 1 Nov 2022 22:48:30 +0900 Subject: [PATCH] perf probe: Fix to avoid crashing if DW_AT_decl_file is NULL Since clang generates DWARF5 which sets DW_AT_decl_file as 0, dwarf_decl_file() thinks that is invalid and returns NULL. In that case 'perf probe' SIGSEGVs because it doesn't expect a NULL decl_file. This adds a dwarf_decl_file() return value check to avoid such SEGV with clang generated DWARF5 info. Without this, 'perf probe' crashes: $ perf probe -k $BIN_PATH/vmlinux -s $SRC_PATH -L vfs_read:10 Segmentation fault $ With this, it just warns about 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 Acked-by: Namhyung Kim Cc: Alexander Shishkin Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mark Rutland Cc: Peter Zijlstra Cc: Steven Rostedt (VMware) Link: https://lore.kernel.org/r/166731051077.2100653.15626653369345128302.stgit@devnote3 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/dwarf-aux.c | 7 ++++++- tools/perf/util/probe-finder.c | 29 +++++++++++++++++++++-------- 2 files changed, 27 insertions(+), 9 deletions(-) diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 609ca1671501..406b7bdc851a 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -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) { diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 50d861a80f57..1aa8fcc41c76 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -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); -- 2.34.1