From 6be581aeffc215bfc77939cd59902b0dbc4af23e Mon Sep 17 00:00:00 2001 From: Chris Gellermann Date: Fri, 4 Sep 2026 11:59:15 +0200 Subject: [PATCH] selftests/nci: Fix out-of-bounds store on thread join The NCI test collects the exit status of its helper threads by passing the address of an int to pthread_join(): int status; ... pthread_join(thread_t, (void **) &status); pthread_join() stores a void pointer to the memory location. On 64-bit systems, a void pointer is wider than an int, so the store overruns the 4 bytes of space allocated on the stack for the integer and corrupts the adjacent stack. On our CHERI system, this caused a fault due to a capability bounds violation. Fix this by introducing a helper that joins a thread through a void pointer and converts the result back to an integer, which is what the helper threads return. While here, also fix the logic in disconnect_tag() if the helper thread creation failed. Previously, it would have joined a thread that was never created when pthread_create() failed. Fixes: f595cf1242f3 ("selftests: Add nci suite") Signed-off-by: Chris Gellermann Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260904095915.3372241-1-christian.gellermann@codasip.com Signed-off-by: David Heidelberg --- tools/testing/selftests/nci/nci_dev.c | 31 +++++++++++++++++---------- 1 file changed, 20 insertions(+), 11 deletions(-) diff --git a/tools/testing/selftests/nci/nci_dev.c b/tools/testing/selftests/nci/nci_dev.c index 23fd38acfcf4..07427fa42888 100644 --- a/tools/testing/selftests/nci/nci_dev.c +++ b/tools/testing/selftests/nci/nci_dev.c @@ -8,6 +8,7 @@ #include #include +#include #include #include #include @@ -87,6 +88,16 @@ struct msgtemplate { char buf[MAX_MSG_SIZE]; }; +static int join_thread_status(pthread_t thread) +{ + void *thread_ret = NULL; + + if (pthread_join(thread, &thread_ret)) + return -1; + + return (int)(intptr_t)thread_ret; +} + static int create_nl_socket(void) { int fd; @@ -444,7 +455,7 @@ FIXTURE_SETUP(NCI) NFC_CMD_DEV_UP, self->dev_idex); EXPECT_EQ(rc, 0); - pthread_join(thread_t, (void **)&status); + status = join_thread_status(thread_t); ASSERT_EQ(status, 0); self->open_state = true; } @@ -514,7 +525,7 @@ FIXTURE_TEARDOWN(NCI) NFC_CMD_DEV_DOWN, self->dev_idex); EXPECT_EQ(rc, 0); - pthread_join(thread_t, (void **)&status); + status = join_thread_status(thread_t); ASSERT_EQ(status, 0); } @@ -585,7 +596,6 @@ int start_polling(int dev_idx, int proto, int virtual_fd, int sd, int fid, int p void *nla_start_poll_data[2] = {&dev_idx, &proto}; int nla_start_poll_len[2] = {4, 4}; pthread_t thread_t; - int status; int rc; rc = pthread_create(&thread_t, NULL, virtual_poll_start, @@ -598,14 +608,12 @@ int start_polling(int dev_idx, int proto, int virtual_fd, int sd, int fid, int p if (rc != 0) return rc; - pthread_join(thread_t, (void **)&status); - return status; + return join_thread_status(thread_t); } int stop_polling(int dev_idx, int virtual_fd, int sd, int fid, int pid) { pthread_t thread_t; - int status; int rc; rc = pthread_create(&thread_t, NULL, virtual_poll_stop, @@ -618,8 +626,7 @@ int stop_polling(int dev_idx, int virtual_fd, int sd, int fid, int pid) if (rc != 0) return rc; - pthread_join(thread_t, (void **)&status); - return status; + return join_thread_status(thread_t); } TEST_F(NCI, start_poll) @@ -834,8 +841,10 @@ int disconnect_tag(int nfc_sock, int virtual_fd) return status; close(nfc_sock); - pthread_join(thread_t, (void **)&status); - return status; + if (status) + return -1; + + return join_thread_status(thread_t); } TEST_F(NCI, t4t_tag_read) @@ -882,7 +891,7 @@ TEST_F(NCI, deinit) NFC_CMD_DEV_DOWN, self->dev_idex); EXPECT_EQ(rc, 0); - pthread_join(thread_t, (void **)&status); + status = join_thread_status(thread_t); self->open_state = 0; ASSERT_EQ(status, 0);