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selftests/prctl: fix non-anonymous VMA mapping in set-anon-vma-name test

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The test creates a non-anonymous VMA (ptr_not_anon) via mmap() with
MAP_PRIVATE but without MAP_ANONYMOUS, using fd=0 (stdin) as the file
descriptor.  This always fails because fd=0 is not a regular file, and the
failure was hidden because ASSERT_NE() incorrectly checked for NULL
instead of MAP_FAILED.

Fix by using mkstemp() + ftruncate() to create a real temporary file, then
mapping it with MAP_PRIVATE to obtain a genuine file-backed VMA.  Also fix
the mmap() error checks to use MAP_FAILED instead of NULL, and pass fd=-1
for the anonymous mapping for clarity.  The temp file is unlinked
immediately so it does not persist on disk.

Link: https://lore.kernel.org/20260803103046.14324-1-hongfu.li@linux.dev
Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hongfu Li
2026-08-03 18:30:46 +08:00
committed by Andrew Morton
parent 809f455a75
commit 8f1d96a16c
1 changed files with 16 additions and 5 deletions
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21
tools/testing/selftests/prctl/set-anon-vma-name-test.c
View File

@@ -4,11 +4,13 @@
*/
#include <errno.h>
#include <fcntl.h>
#include <sys/prctl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <unistd.h>
#include "kselftest_harness.h"
@@ -73,15 +75,24 @@ int was_renaming_successful(char *target_name, unsigned long ptr)
FIXTURE(vma) {
void *ptr_anon, *ptr_not_anon;
int fd_not_anon;
};
FIXTURE_SETUP(vma) {
char template[] = "./set-anon-vma-test-XXXXXX";
self->ptr_anon = mmap(NULL, AREA_SIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
ASSERT_NE(self->ptr_anon, NULL);
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
ASSERT_NE(self->ptr_anon, MAP_FAILED);
self->fd_not_anon = mkstemp(template);
ASSERT_NE(self->fd_not_anon, -1);
unlink(template);
ASSERT_EQ(ftruncate(self->fd_not_anon, AREA_SIZE), 0);
self->ptr_not_anon = mmap(NULL, AREA_SIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE, 0, 0);
ASSERT_NE(self->ptr_not_anon, NULL);
MAP_PRIVATE, self->fd_not_anon, 0);
ASSERT_NE(self->ptr_not_anon, MAP_FAILED);
close(self->fd_not_anon);
}
FIXTURE_TEARDOWN(vma) {
@@ -98,7 +109,7 @@ TEST_F(vma, renaming) {
EXPECT_EQ(rename_vma((unsigned long)self->ptr_anon, AREA_SIZE, BAD_NAME), -EINVAL);
TH_LOG("Try to rename non-anonymous VMA");
EXPECT_EQ(rename_vma((unsigned long) self->ptr_not_anon, AREA_SIZE, GOOD_NAME), -EINVAL);
EXPECT_EQ(rename_vma((unsigned long) self->ptr_not_anon, AREA_SIZE, GOOD_NAME), -EBADF);
}
TEST_HARNESS_MAIN