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authorPeilin Ye <peilin.ye@bytedance.com>2022-08-03 15:23:43 -0700
committerJens Axboe <axboe@kernel.dk>2022-08-04 08:33:54 -0600
commitf482aa98652795846cc55da98ebe331eb74f3d0b (patch)
tree6cb094583f2ef7c0d9d5bfeab129145e0fa07cd2
parentff2557b7224ea9a19fb79eb4bd16d4deef57816a (diff)
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: [<ffffffff8135cfc3>] audit_alloc+0x133/0x210 [<ffffffff81239e63>] copy_process+0xcd3/0x2340 [<ffffffff8123b5f3>] create_io_thread+0x63/0x90 [<ffffffff81686604>] create_io_worker+0xb4/0x230 [<ffffffff81686f68>] io_wqe_enqueue+0x248/0x3b0 [<ffffffff8167663a>] io_queue_iowq+0xba/0x200 [<ffffffff816768b3>] io_queue_async+0x113/0x180 [<ffffffff816840df>] io_req_task_submit+0x18f/0x1a0 [<ffffffff816841cd>] io_apoll_task_func+0xdd/0x120 [<ffffffff8167d49f>] tctx_task_work+0x11f/0x570 [<ffffffff81272c4e>] task_work_run+0x7e/0xc0 [<ffffffff8125a688>] get_signal+0xc18/0xf10 [<ffffffff8111645b>] arch_do_signal_or_restart+0x2b/0x730 [<ffffffff812ea44e>] exit_to_user_mode_prepare+0x5e/0x180 [<ffffffff844ae1b2>] syscall_exit_to_user_mode+0x12/0x20 [<ffffffff844a7e80>] 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 <paul@paul-moore.com> Cc: stable@vger.kernel.org Signed-off-by: Peilin Ye <peilin.ye@bytedance.com> Acked-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20220803222343.31673-1-yepeilin.cs@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--include/linux/audit.h5
-rw-r--r--io_uring/io-wq.c3
-rw-r--r--io_uring/sqpoll.c4
-rw-r--r--kernel/auditsc.c25
4 files changed, 0 insertions, 37 deletions
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 00f7a80f1a3e..3608992848d3 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -285,7 +285,6 @@ static inline int audit_signal_info(int sig, struct task_struct *t)
/* These are defined in auditsc.c */
/* Public API */
extern int audit_alloc(struct task_struct *task);
-extern int audit_alloc_kernel(struct task_struct *task);
extern void __audit_free(struct task_struct *task);
extern void __audit_uring_entry(u8 op);
extern void __audit_uring_exit(int success, long code);
@@ -578,10 +577,6 @@ static inline int audit_alloc(struct task_struct *task)
{
return 0;
}
-static inline int audit_alloc_kernel(struct task_struct *task)
-{
- return 0;
-}
static inline void audit_free(struct task_struct *task)
{ }
static inline void audit_uring_entry(u8 op)
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);
}
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 3a8c9d744800..dd8d9ab747c3 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1073,31 +1073,6 @@ int audit_alloc(struct task_struct *tsk)
return 0;
}
-/**
- * audit_alloc_kernel - allocate an audit_context for a kernel task
- * @tsk: the kernel task
- *
- * Similar to the audit_alloc() function, but intended for kernel private
- * threads. Returns zero on success, negative values on failure.
- */
-int audit_alloc_kernel(struct task_struct *tsk)
-{
- /*
- * At the moment we are just going to call into audit_alloc() to
- * simplify the code, but there two things to keep in mind with this
- * approach:
- *
- * 1. Filtering internal kernel tasks is a bit laughable in almost all
- * cases, but there is at least one case where there is a benefit:
- * the '-a task,never' case allows the admin to effectively disable
- * task auditing at runtime.
- *
- * 2. The {set,clear}_task_syscall_work() ops likely have zero effect
- * on these internal kernel tasks, but they probably don't hurt either.
- */
- return audit_alloc(tsk);
-}
-
static inline void audit_free_context(struct audit_context *context)
{
/* resetting is extra work, but it is likely just noise */