From 2cc1c01fe97703d9d694fa49b16fb3aab47b70a9 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:25 +0100 Subject: [PATCH] selftests/namespace: test listns() pagination Minimal test case to reproduce KASAN out-of-bounds in listns pagination. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-72-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 4 +- .../namespaces/listns_pagination_bug.c | 138 ++++++++++++++++++ 3 files changed, 142 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/listns_pagination_bug.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index f6dcf769f1505..f4d2209ca4e44 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -7,3 +7,4 @@ listns_permissions_test siocgskns_test cred_change_test stress_test +listns_pagination_bug diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index 3c776740f3ac4..01569e0abbdb0 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -10,7 +10,8 @@ TEST_GEN_PROGS := nsid_test \ listns_permissions_test \ siocgskns_test \ cred_change_test \ - stress_test + stress_test \ + listns_pagination_bug include ../lib.mk @@ -20,4 +21,5 @@ $(OUTPUT)/listns_permissions_test: ../filesystems/utils.c $(OUTPUT)/siocgskns_test: ../filesystems/utils.c $(OUTPUT)/cred_change_test: ../filesystems/utils.c $(OUTPUT)/stress_test: ../filesystems/utils.c +$(OUTPUT)/listns_pagination_bug: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/listns_pagination_bug.c b/tools/testing/selftests/namespaces/listns_pagination_bug.c new file mode 100644 index 0000000000000..da7d33f963972 --- /dev/null +++ b/tools/testing/selftests/namespaces/listns_pagination_bug.c @@ -0,0 +1,138 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +/* + * Minimal test case to reproduce KASAN out-of-bounds in listns pagination. + * + * The bug occurs when: + * 1. Filtering by a specific namespace type (e.g., CLONE_NEWUSER) + * 2. Using pagination (req.ns_id != 0) + * 3. The lookup_ns_id_at() call in do_listns() passes ns_type=0 instead of + * the filtered type, causing it to search the unified tree and potentially + * return a namespace of the wrong type. + */ +TEST(pagination_with_type_filter) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, /* Filter by user namespace */ + .spare2 = 0, + .user_ns_id = 0, + }; + pid_t pids[10]; + int num_children = 10; + int i; + int sv[2]; + __u64 first_batch[3]; + ssize_t ret; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + /* Create children with user namespaces */ + for (i = 0; i < num_children; i++) { + pids[i] = fork(); + ASSERT_GE(pids[i], 0); + + if (pids[i] == 0) { + char c; + close(sv[0]); + + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + /* Signal parent we're ready */ + if (write(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + /* Wait for parent signal to exit */ + if (read(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + close(sv[1]); + exit(0); + } + } + + close(sv[1]); + + /* Wait for all children to signal ready */ + for (i = 0; i < num_children; i++) { + char c; + if (read(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = 0; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + /* First batch - this should work */ + ret = sys_listns(&req, first_batch, 3, 0); + if (ret < 0) { + if (errno == ENOSYS) { + close(sv[0]); + for (i = 0; i < num_children; i++) + kill(pids[i], SIGKILL); + for (i = 0; i < num_children; i++) + waitpid(pids[i], NULL, 0); + SKIP(return, "listns() not supported"); + } + ASSERT_GE(ret, 0); + } + + TH_LOG("First batch returned %zd entries", ret); + + if (ret == 3) { + __u64 second_batch[3]; + + /* Second batch - pagination triggers the bug */ + req.ns_id = first_batch[2]; /* Continue from last ID */ + ret = sys_listns(&req, second_batch, 3, 0); + + TH_LOG("Second batch returned %zd entries", ret); + ASSERT_GE(ret, 0); + } + + /* Signal all children to exit */ + for (i = 0; i < num_children; i++) { + char c = 'X'; + if (write(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = i; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + close(sv[0]); + + /* Cleanup */ + for (i = 0; i < num_children; i++) { + int status; + waitpid(pids[i], &status, 0); + } +} + +TEST_HARNESS_MAIN -- 2.47.3