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perf libdw: Fix libdw API contract violations and memory leaks

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Check return values of `dwfl_report_end` and `dwfl_module_addrdie`
to prevent using uninitialized stack variables or reporting success on
failure.

Additionally:
 - Ensure `*file` is freed and inline frames are cleared on error in
   `libdw__addr2line()` to prevent memory leaks and duplicated
   callchains when falling back to other unwinders.
 - Use `die_name()` safe wrapper inside the inline function unwinding
   callback (`libdw_a2l_cb`).
 - Refactor `libdw_a2l_cb`'s repeated memory error handling/cleanup
   paths using a cleaner goto control flow.

Fixes: b7a2b011e9 ("perf powerpc: Unify the skip-callchain-idx libdw with that for addr2line")
Fixes: 88c51002d0 ("perf addr2line: Add a libdw implementation")
Assisted-by: Gemini-CLI:Google Gemini 3
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2026-05-04 01:12:24 -07:00 committed by Arnaldo Carvalho de Melo
parent 15f8c22c46
commit 9c6d535ddb
1 changed files with 43 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
tools/perf/util/libdw.c
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@ -61,7 +61,10 @@ struct Dwfl *dso__libdw_dwfl(struct dso *dso)
return NULL;
}
dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL);
if (dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL) != 0) {
dwfl_end(dwfl);
return NULL;
}
dso__set_libdw(dso, dwfl);
return dwfl;
@ -73,18 +76,19 @@ struct libdw_a2l_cb_args {
struct inline_node *node;
char *leaf_srcline;
bool leaf_srcline_used;
int err;
};
static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
{
struct libdw_a2l_cb_args *args = _args;
struct symbol *inline_sym = new_inline_sym(args->dso, args->sym, dwarf_diename(die));
struct symbol *inline_sym = new_inline_sym(args->dso, args->sym, die_name(die));
const char *call_fname = die_get_call_file(die);
int call_lineno = die_get_call_lineno(die);
char *call_srcline = srcline__unknown;
if (!inline_sym)
return -ENOMEM;
goto abort_enomem;
/* Assign caller information to the parent. */
if (call_fname)
@ -110,12 +114,27 @@ static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
/* Add this symbol to the chain as the leaf. */
if (!args->leaf_srcline_used) {
inline_list__append_tail(inline_sym, args->leaf_srcline, args->node);
if (inline_list__append_tail(inline_sym, args->leaf_srcline, args->node) != 0)
goto abort_delete_sym;
args->leaf_srcline_used = true;
} else {
inline_list__append_tail(inline_sym, strdup(args->leaf_srcline), args->node);
char *srcline = strdup(args->leaf_srcline);
if (!srcline)
goto abort_delete_sym;
if (inline_list__append_tail(inline_sym, srcline, args->node) != 0) {
free(srcline);
goto abort_delete_sym;
}
}
return 0;
abort_delete_sym:
if (inline_sym->inlined)
symbol__delete(inline_sym);
abort_enomem:
args->err = -ENOMEM;
return DWARF_CB_ABORT;
}
int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr,
@ -169,11 +188,29 @@ int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr,
.leaf_srcline = srcline_from_fileline(src ?: "<unknown>", lineno),
};
if (!args.leaf_srcline) {
if (file && *file) {
free(*file);
*file = NULL;
}
return 0;
}
/* Walk from the parent down to the leaf. */
cu_walk_functions_at(cudie, addr, libdw_a2l_cb, &args);
if (cudie)
cu_walk_functions_at(cudie, addr, libdw_a2l_cb, &args);
if (!args.leaf_srcline_used)
free(args.leaf_srcline);
if (args.err) {
if (file && *file) {
free(*file);
*file = NULL;
}
inline_node__clear_frames(node);
return 0;
}
}
return 1;
}