>From 8f6aeb362d9e44f29d46ae7694cdfee4408406ce Mon Sep 17 00:00:00 2001
From: "KIM JUGNBAE" <jb09.kim@xxxxxxxxxxx>
Date: Thu, 26 Nov 2015 16:28:47 +0900
Subject: [PATCH] bug_fix : access freed memory
sync_fenc_free & fence_check_cb_func would be executed at
other cpu. fence_check_cb_func access freed fence memory after
kfree(fence) at sync_fence_free.
To escaped this issue, atomic_read(&fence->status) need to be
protected by child_list_lock.
Signed-off-by: "kimjungbae\" " <jb09.kim@xxxxxxxxxxx>"
---
drivers/dma-buf/fence.c | 13 +++++++++++++
drivers/staging/android/sync.c | 10 +++++++---
drivers/staging/android/sync_debug.c | 2 ++
include/linux/fence.h | 1 +
4 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c
index 7bb9d65..d40211e 100644
--- a/drivers/dma-buf/fence.c
+++ b/drivers/dma-buf/fence.c
@@ -310,6 +310,19 @@ fence_remove_callback(struct fence *fence, struct fence_cb *cb)
}
EXPORT_SYMBOL(fence_remove_callback);
+bool
+fence_remove_callback_locked(struct fence *fence, struct fence_cb *cb)
+{
+ bool ret;
+
+ ret = !list_empty(&cb->node);
+ if (ret)
+ list_del_init(&cb->node);
+
+ return ret;
+}
+EXPORT_SYMBOL(fence_remove_callback_locked);
+
struct default_wait_cb {
struct fence_cb base;
struct task_struct *task;
diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index 83f640f..9b60542 100644
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -518,12 +518,16 @@ static const struct fence_ops android_fence_ops = {
static void sync_fence_free(struct kref *kref)
{
struct sync_fence *fence = container_of(kref, struct sync_fence, kref);
- int i, status = atomic_read(&fence->status);
+ int i;
+ unsigned long flags;
for (i = 0; i < fence->num_fences; ++i) {
- if (status)
- fence_remove_callback(fence->cbs[i].sync_pt,
+ spin_lock_irqsave(fence->cbs[i].sync_pt->lock, flags);
+ if (atomic_read(&fence->status))
+ fence_remove_callback_locked(fence->cbs[i].sync_pt,
&fence->cbs[i].cb);
+ spin_unlock_irqrestore(fence->cbs[i].sync_pt->lock, flags);
+
fence_put(fence->cbs[i].sync_pt);
}
diff --git a/drivers/staging/android/sync_debug.c b/drivers/staging/android/sync_debug.c
index 0153cd2..e854f35 100644
--- a/drivers/staging/android/sync_debug.c
+++ b/drivers/staging/android/sync_debug.c
@@ -155,7 +155,9 @@ static void sync_print_fence(struct seq_file *s, struct sync_fence *fence)
container_of(fence->cbs[i].sync_pt,
struct sync_pt, base);
+ spin_lock_irqsave(pt->base.lock, flags);
sync_print_pt(s, pt, true);
+ spin_unlock_irqrestore(pt->base.lock, flags);
}
spin_lock_irqsave(&fence->wq.lock, flags);
diff --git a/include/linux/fence.h b/include/linux/fence.h
index d174585..a5a3fd1 100644
--- a/include/linux/fence.h
+++ b/include/linux/fence.h
@@ -224,6 +224,7 @@ signed long fence_default_wait(struct fence *fence, bool intr, signed long timeo
int fence_add_callback(struct fence *fence, struct fence_cb *cb,
fence_func_t func);
bool fence_remove_callback(struct fence *fence, struct fence_cb *cb);
+bool fence_remove_callback_locked(struct fence *fence, struct fence_cb *cb);
void fence_enable_sw_signaling(struct fence *fence);
/**
--
1.7.9.5
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