From f482aa98652795846cc55da98ebe331eb74f3d0b Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Wed, 3 Aug 2022 15:23:43 -0700 Subject: audit, io_uring, io-wq: Fix memory leak in io_sq_thread() and io_wqe_worker() Currently @audit_context is allocated twice for io_uring workers: 1. copy_process() calls audit_alloc(); 2. io_sq_thread() or io_wqe_worker() calls audit_alloc_kernel() (which is effectively audit_alloc()) and overwrites @audit_context, causing: BUG: memory leak unreferenced object 0xffff888144547400 (size 1024): <...> hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] audit_alloc+0x133/0x210 [] copy_process+0xcd3/0x2340 [] create_io_thread+0x63/0x90 [] create_io_worker+0xb4/0x230 [] io_wqe_enqueue+0x248/0x3b0 [] io_queue_iowq+0xba/0x200 [] io_queue_async+0x113/0x180 [] io_req_task_submit+0x18f/0x1a0 [] io_apoll_task_func+0xdd/0x120 [] tctx_task_work+0x11f/0x570 [] task_work_run+0x7e/0xc0 [] get_signal+0xc18/0xf10 [] arch_do_signal_or_restart+0x2b/0x730 [] exit_to_user_mode_prepare+0x5e/0x180 [] syscall_exit_to_user_mode+0x12/0x20 [] do_syscall_64+0x40/0x80 Then, 3. io_sq_thread() or io_wqe_worker() frees @audit_context using audit_free(); 4. do_exit() eventually calls audit_free() again, which is okay because audit_free() does a NULL check. As suggested by Paul Moore, fix it by deleting audit_alloc_kernel() and redundant audit_free() calls. Fixes: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit support to io_uring") Suggested-by: Paul Moore Cc: stable@vger.kernel.org Signed-off-by: Peilin Ye Acked-by: Paul Moore Link: https://lore.kernel.org/r/20220803222343.31673-1-yepeilin.cs@gmail.com Signed-off-by: Jens Axboe --- io_uring/io-wq.c | 3 --- io_uring/sqpoll.c | 4 ---- 2 files changed, 7 deletions(-) (limited to 'io_uring') diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index 77df5b43bf52..c6536d4b2da0 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -624,8 +624,6 @@ static int io_wqe_worker(void *data) snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid); set_task_comm(current, buf); - audit_alloc_kernel(current); - while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) { long ret; @@ -660,7 +658,6 @@ static int io_wqe_worker(void *data) if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) io_worker_handle_work(worker); - audit_free(current); io_worker_exit(worker); return 0; } diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c index 76d4d70c733a..559652380672 100644 --- a/io_uring/sqpoll.c +++ b/io_uring/sqpoll.c @@ -235,8 +235,6 @@ static int io_sq_thread(void *data) set_cpus_allowed_ptr(current, cpu_online_mask); current->flags |= PF_NO_SETAFFINITY; - audit_alloc_kernel(current); - mutex_lock(&sqd->lock); while (1) { bool cap_entries, sqt_spin = false; @@ -310,8 +308,6 @@ static int io_sq_thread(void *data) io_run_task_work(); mutex_unlock(&sqd->lock); - audit_free(current); - complete(&sqd->exited); do_exit(0); } -- cgit v1.2.3-59-g8ed1b