[PATCH 6.19 019/311] objtool/klp: fix mkstemp() failure with long paths

Greg Kroah-Hartman
2026-04-08T18:50:34Z

From: Joe Lawrence <joe.lawrence@redhat.com>

[ Upstream commit 28e367a969b0c54c87ca655ec180715fe469fd14 ]

The elf_create_file() function fails with EINVAL when the build directory
path is long enough to truncate the "XXXXXX" suffix in the 256-byte
tmp_name buffer.

Simplify the code to remove the unnecessary dirname()/basename() split
and concatenation. Instead, allocate the exact number of bytes needed for
the path.

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Link: https://patch.msgid.link/20260310203751.1479229-3-joe.lawrence@redhat.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/objtool/elf.c | 23 +++--------------------
1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 3da90686350d7..2ffe3ebfbe37c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -16,7 +16,6 @@
#include <string.h>
#include <unistd.h>
#include <errno.h>
-#include <libgen.h>
#include <ctype.h>
#include <linux/align.h>
#include <linux/kernel.h>
@@ -1189,7 +1188,7 @@ struct elf *elf_open_read(const char *name, int flags)
struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)
{
struct section *null, *symtab, *strtab, *shstrtab;
- char *dir, *base, *tmp_name;
+ char *tmp_name;
struct symbol *sym;
struct elf *elf;

@@ -1203,29 +1202,13 @@ struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)

INIT_LIST_HEAD(&elf->sections);

- dir = strdup(name);
- if (!dir) {
- ERROR_GLIBC("strdup");
- return NULL;
- }
-
- dir = dirname(dir);
-
- base = strdup(name);
- if (!base) {
- ERROR_GLIBC("strdup");
- return NULL;
- }
-
- base = basename(base);
-
- tmp_name = malloc(256);
+ tmp_name = malloc(strlen(name) + 8);
if (!tmp_name) {
ERROR_GLIBC("malloc");
return NULL;
}

- snprintf(tmp_name, 256, "%s/%s.XXXXXX", dir, base);
+ sprintf(tmp_name, "%s.XXXXXX", name);

elf->fd = mkstemp(tmp_name);
if (elf->fd == -1) {
--
2.53.0