* [RFC PATCH] staging/android/ion : fix a race condition in the ion driver
@ 2016-02-17 6:32 EunTaik Lee
2016-02-17 18:54 ` Laura Abbott
0 siblings, 1 reply; 2+ messages in thread
From: EunTaik Lee @ 2016-02-17 6:32 UTC (permalink / raw)
To: gregkh, arve, riandrews, labbott, sumit.semwal, gioh.kim,
dan.carpenter, rohit.kr, sriram, shawn.lin, eun.taik.lee, devel,
linux-kernel
There was a use-after-free problem in the ion driver.
The problem is detected as an unaligned access in the
spin lock functions since it uses load exclusive
instruction. In some cases it corrupts the slub's
free pointer which causes a unaligned access to the
next free pointer.(thus the kmalloc function returns
a pointer like ffffc0745b4580aa). And it causes lots of other
hard-to-debug problems.
This symptom is caused since the first member in the
ion_handle structure is the reference count and the
ion driver decrements the reference after it has been
freed.
To fix this problem client->lock mutex is extended
to protect all the codes that uses the handle.
Signed-off-by: Eun Taik Lee <eun.taik.lee@samsung.com>
---
drivers/staging/android/ion/ion.c | 102 ++++++++++++++++++++++++++++++--------
1 file changed, 82 insertions(+), 20 deletions(-)
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index e237e9f..cb03b59 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -385,13 +385,22 @@ static void ion_handle_get(struct ion_handle *handle)
kref_get(&handle->ref);
}
+static int ion_handle_put_nolock(struct ion_handle *handle)
+{
+ int ret;
+
+ ret = kref_put(&handle->ref, ion_handle_destroy);
+
+ return ret;
+}
+
static int ion_handle_put(struct ion_handle *handle)
{
struct ion_client *client = handle->client;
int ret;
mutex_lock(&client->lock);
- ret = kref_put(&handle->ref, ion_handle_destroy);
+ ret = ion_handle_put_nolock(handle);
mutex_unlock(&client->lock);
return ret;
@@ -415,20 +424,30 @@ static struct ion_handle *ion_handle_lookup(struct ion_client *client,
return ERR_PTR(-EINVAL);
}
-static struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
- int id)
+static struct ion_handle *ion_handle_get_by_id_nolock(struct ion_client *client,
+ int id)
{
struct ion_handle *handle;
- mutex_lock(&client->lock);
handle = idr_find(&client->idr, id);
if (handle)
ion_handle_get(handle);
- mutex_unlock(&client->lock);
return handle ? handle : ERR_PTR(-EINVAL);
}
+struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
+ int id)
+{
+ struct ion_handle *handle;
+
+ mutex_lock(&client->lock);
+ handle = ion_handle_get_by_id_nolock(client, id);
+ mutex_unlock(&client->lock);
+
+ return handle;
+}
+
static bool ion_handle_validate(struct ion_client *client,
struct ion_handle *handle)
{
@@ -530,7 +549,8 @@ struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
}
EXPORT_SYMBOL(ion_alloc);
-void ion_free(struct ion_client *client, struct ion_handle *handle)
+static void ion_free_nolock(struct ion_client *client,
+ struct ion_handle *handle)
{
bool valid_handle;
@@ -538,15 +558,24 @@ void ion_free(struct ion_client *client, struct ion_handle *handle)
mutex_lock(&client->lock);
valid_handle = ion_handle_validate(client, handle);
-
if (!valid_handle) {
WARN(1, "%s: invalid handle passed to free.\n", __func__);
mutex_unlock(&client->lock);
return;
}
+ ion_handle_put_nolock(handle);
+}
+
+void ion_free(struct ion_client *client, struct ion_handle *handle)
+{
+ BUG_ON(client != handle->client);
+
+ mutex_lock(&client->lock);
+ ion_free_nolock(client, handle);
mutex_unlock(&client->lock);
ion_handle_put(handle);
}
+
EXPORT_SYMBOL(ion_free);
int ion_phys(struct ion_client *client, struct ion_handle *handle,
@@ -830,6 +859,7 @@ void ion_client_destroy(struct ion_client *client)
struct rb_node *n;
pr_debug("%s: %d\n", __func__, __LINE__);
+ mutex_lock(&client->lock);
while ((n = rb_first(&client->handles))) {
struct ion_handle *handle = rb_entry(n, struct ion_handle,
node);
@@ -837,6 +867,7 @@ void ion_client_destroy(struct ion_client *client)
}
idr_destroy(&client->idr);
+ mutex_unlock(&client->lock);
down_write(&dev->lock);
if (client->task)
@@ -1100,7 +1131,7 @@ static struct dma_buf_ops dma_buf_ops = {
.kunmap = ion_dma_buf_kunmap,
};
-struct dma_buf *ion_share_dma_buf(struct ion_client *client,
+static struct dma_buf *ion_share_dma_buf_nolock(struct ion_client *client,
struct ion_handle *handle)
{
DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
@@ -1108,7 +1139,6 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
struct dma_buf *dmabuf;
bool valid_handle;
- mutex_lock(&client->lock);
valid_handle = ion_handle_validate(client, handle);
if (!valid_handle) {
WARN(1, "%s: invalid handle passed to share.\n", __func__);
@@ -1117,7 +1147,6 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
}
buffer = handle->buffer;
ion_buffer_get(buffer);
- mutex_unlock(&client->lock);
exp_info.ops = &dma_buf_ops;
exp_info.size = buffer->size;
@@ -1132,14 +1161,26 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
return dmabuf;
}
+
+struct dma_buf *ion_share_dma_buf(struct ion_client *client,
+ struct ion_handle *handle)
+{
+ struct dma_buf *dmabuf;
+
+ mutex_lock(&client->lock);
+ dmabuf = ion_share_dma_buf_nolock(client, handle);
+ mutex_unlock(&client->lock);
+ return dmabuf;
+}
EXPORT_SYMBOL(ion_share_dma_buf);
-int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
+static int ion_share_dma_buf_fd_nolock(struct ion_client *client,
+ struct ion_handle *handle)
{
struct dma_buf *dmabuf;
int fd;
- dmabuf = ion_share_dma_buf(client, handle);
+ dmabuf = ion_share_dma_buf_nolock(client, handle);
if (IS_ERR(dmabuf))
return PTR_ERR(dmabuf);
@@ -1149,6 +1190,17 @@ int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
return fd;
}
+
+int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
+{
+ int fd;
+
+ mutex_lock(&client->lock);
+ fd = ion_share_dma_buf_fd_nolock(client, handle);
+ mutex_lock(&client->lock);
+
+ return fd;
+}
EXPORT_SYMBOL(ion_share_dma_buf_fd);
struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
@@ -1281,11 +1333,16 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct ion_handle *handle;
- handle = ion_handle_get_by_id(client, data.handle.handle);
- if (IS_ERR(handle))
+ mutex_lock(&client->lock);
+ handle = ion_handle_get_by_id_nolock(client,
+ data.handle.handle);
+ if (IS_ERR(handle)) {
+ mutex_unlock(&client->lock);
return PTR_ERR(handle);
- ion_free(client, handle);
- ion_handle_put(handle);
+ }
+ ion_free_nolock(client, handle);
+ ion_handle_put_nolock(handle);
+ mutex_unlock(&client->lock);
break;
}
case ION_IOC_SHARE:
@@ -1293,11 +1350,16 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct ion_handle *handle;
- handle = ion_handle_get_by_id(client, data.handle.handle);
- if (IS_ERR(handle))
+ mutex_lock(&client->lock);
+ handle = ion_handle_get_by_id_nolock(client,
+ data.handle.handle);
+ if (IS_ERR(handle)) {
+ mutex_unlock(&client->lock);
return PTR_ERR(handle);
- data.fd.fd = ion_share_dma_buf_fd(client, handle);
- ion_handle_put(handle);
+ }
+ data.fd.fd = ion_share_dma_buf_fd_nolock(client, handle);
+ ion_handle_put_nolock(handle);
+ mutex_unlock(&client->lock);
if (data.fd.fd < 0)
ret = data.fd.fd;
break;
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RFC PATCH] staging/android/ion : fix a race condition in the ion driver
2016-02-17 6:32 [RFC PATCH] staging/android/ion : fix a race condition in the ion driver EunTaik Lee
@ 2016-02-17 18:54 ` Laura Abbott
0 siblings, 0 replies; 2+ messages in thread
From: Laura Abbott @ 2016-02-17 18:54 UTC (permalink / raw)
To: eun.taik.lee, gregkh, arve, riandrews, sumit.semwal, gioh.kim,
dan.carpenter, rohit.kr, sriram, shawn.lin, devel, linux-kernel
On 02/16/2016 10:32 PM, EunTaik Lee wrote:
> There was a use-after-free problem in the ion driver.
>
> The problem is detected as an unaligned access in the
> spin lock functions since it uses load exclusive
> instruction. In some cases it corrupts the slub's
> free pointer which causes a unaligned access to the
> next free pointer.(thus the kmalloc function returns
> a pointer like ffffc0745b4580aa). And it causes lots of other
> hard-to-debug problems.
>
> This symptom is caused since the first member in the
> ion_handle structure is the reference count and the
> ion driver decrements the reference after it has been
> freed.
>
> To fix this problem client->lock mutex is extended
> to protect all the codes that uses the handle.
>
This describes the symptoms very well but what's the actual
race condition?
Also what tree did you generate this against? It doesn't
seem to apply.
Thanks,
Laura
> Signed-off-by: Eun Taik Lee <eun.taik.lee@samsung.com>
> ---
> drivers/staging/android/ion/ion.c | 102 ++++++++++++++++++++++++++++++--------
> 1 file changed, 82 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index e237e9f..cb03b59 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -385,13 +385,22 @@ static void ion_handle_get(struct ion_handle *handle)
> kref_get(&handle->ref);
> }
>
> +static int ion_handle_put_nolock(struct ion_handle *handle)
> +{
> + int ret;
> +
> + ret = kref_put(&handle->ref, ion_handle_destroy);
> +
> + return ret;
> +}
> +
> static int ion_handle_put(struct ion_handle *handle)
> {
> struct ion_client *client = handle->client;
> int ret;
>
> mutex_lock(&client->lock);
> - ret = kref_put(&handle->ref, ion_handle_destroy);
> + ret = ion_handle_put_nolock(handle);
> mutex_unlock(&client->lock);
>
> return ret;
> @@ -415,20 +424,30 @@ static struct ion_handle *ion_handle_lookup(struct ion_client *client,
> return ERR_PTR(-EINVAL);
> }
>
> -static struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
> - int id)
> +static struct ion_handle *ion_handle_get_by_id_nolock(struct ion_client *client,
> + int id)
> {
> struct ion_handle *handle;
>
> - mutex_lock(&client->lock);
> handle = idr_find(&client->idr, id);
> if (handle)
> ion_handle_get(handle);
> - mutex_unlock(&client->lock);
>
> return handle ? handle : ERR_PTR(-EINVAL);
> }
>
> +struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
> + int id)
> +{
> + struct ion_handle *handle;
> +
> + mutex_lock(&client->lock);
> + handle = ion_handle_get_by_id_nolock(client, id);
> + mutex_unlock(&client->lock);
> +
> + return handle;
> +}
> +
> static bool ion_handle_validate(struct ion_client *client,
> struct ion_handle *handle)
> {
> @@ -530,7 +549,8 @@ struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
> }
> EXPORT_SYMBOL(ion_alloc);
>
> -void ion_free(struct ion_client *client, struct ion_handle *handle)
> +static void ion_free_nolock(struct ion_client *client,
> + struct ion_handle *handle)
> {
> bool valid_handle;
>
> @@ -538,15 +558,24 @@ void ion_free(struct ion_client *client, struct ion_handle *handle)
>
> mutex_lock(&client->lock);
> valid_handle = ion_handle_validate(client, handle);
> -
> if (!valid_handle) {
> WARN(1, "%s: invalid handle passed to free.\n", __func__);
> mutex_unlock(&client->lock);
> return;
> }
> + ion_handle_put_nolock(handle);
> +}
> +
> +void ion_free(struct ion_client *client, struct ion_handle *handle)
> +{
> + BUG_ON(client != handle->client);
> +
> + mutex_lock(&client->lock);
> + ion_free_nolock(client, handle);
> mutex_unlock(&client->lock);
> ion_handle_put(handle);
> }
> +
> EXPORT_SYMBOL(ion_free);
>
> int ion_phys(struct ion_client *client, struct ion_handle *handle,
> @@ -830,6 +859,7 @@ void ion_client_destroy(struct ion_client *client)
> struct rb_node *n;
>
> pr_debug("%s: %d\n", __func__, __LINE__);
> + mutex_lock(&client->lock);
> while ((n = rb_first(&client->handles))) {
> struct ion_handle *handle = rb_entry(n, struct ion_handle,
> node);
> @@ -837,6 +867,7 @@ void ion_client_destroy(struct ion_client *client)
> }
>
> idr_destroy(&client->idr);
> + mutex_unlock(&client->lock);
>
> down_write(&dev->lock);
> if (client->task)
> @@ -1100,7 +1131,7 @@ static struct dma_buf_ops dma_buf_ops = {
> .kunmap = ion_dma_buf_kunmap,
> };
>
> -struct dma_buf *ion_share_dma_buf(struct ion_client *client,
> +static struct dma_buf *ion_share_dma_buf_nolock(struct ion_client *client,
> struct ion_handle *handle)
> {
> DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> @@ -1108,7 +1139,6 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
> struct dma_buf *dmabuf;
> bool valid_handle;
>
> - mutex_lock(&client->lock);
> valid_handle = ion_handle_validate(client, handle);
> if (!valid_handle) {
> WARN(1, "%s: invalid handle passed to share.\n", __func__);
> @@ -1117,7 +1147,6 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
> }
> buffer = handle->buffer;
> ion_buffer_get(buffer);
> - mutex_unlock(&client->lock);
>
> exp_info.ops = &dma_buf_ops;
> exp_info.size = buffer->size;
> @@ -1132,14 +1161,26 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
>
> return dmabuf;
> }
> +
> +struct dma_buf *ion_share_dma_buf(struct ion_client *client,
> + struct ion_handle *handle)
> +{
> + struct dma_buf *dmabuf;
> +
> + mutex_lock(&client->lock);
> + dmabuf = ion_share_dma_buf_nolock(client, handle);
> + mutex_unlock(&client->lock);
> + return dmabuf;
> +}
> EXPORT_SYMBOL(ion_share_dma_buf);
>
> -int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
> +static int ion_share_dma_buf_fd_nolock(struct ion_client *client,
> + struct ion_handle *handle)
> {
> struct dma_buf *dmabuf;
> int fd;
>
> - dmabuf = ion_share_dma_buf(client, handle);
> + dmabuf = ion_share_dma_buf_nolock(client, handle);
> if (IS_ERR(dmabuf))
> return PTR_ERR(dmabuf);
>
> @@ -1149,6 +1190,17 @@ int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
>
> return fd;
> }
> +
> +int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
> +{
> + int fd;
> +
> + mutex_lock(&client->lock);
> + fd = ion_share_dma_buf_fd_nolock(client, handle);
> + mutex_lock(&client->lock);
> +
> + return fd;
> +}
> EXPORT_SYMBOL(ion_share_dma_buf_fd);
>
> struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
> @@ -1281,11 +1333,16 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct ion_handle *handle;
>
> - handle = ion_handle_get_by_id(client, data.handle.handle);
> - if (IS_ERR(handle))
> + mutex_lock(&client->lock);
> + handle = ion_handle_get_by_id_nolock(client,
> + data.handle.handle);
> + if (IS_ERR(handle)) {
> + mutex_unlock(&client->lock);
> return PTR_ERR(handle);
> - ion_free(client, handle);
> - ion_handle_put(handle);
> + }
> + ion_free_nolock(client, handle);
> + ion_handle_put_nolock(handle);
> + mutex_unlock(&client->lock);
> break;
> }
> case ION_IOC_SHARE:
> @@ -1293,11 +1350,16 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct ion_handle *handle;
>
> - handle = ion_handle_get_by_id(client, data.handle.handle);
> - if (IS_ERR(handle))
> + mutex_lock(&client->lock);
> + handle = ion_handle_get_by_id_nolock(client,
> + data.handle.handle);
> + if (IS_ERR(handle)) {
> + mutex_unlock(&client->lock);
> return PTR_ERR(handle);
> - data.fd.fd = ion_share_dma_buf_fd(client, handle);
> - ion_handle_put(handle);
> + }
> + data.fd.fd = ion_share_dma_buf_fd_nolock(client, handle);
> + ion_handle_put_nolock(handle);
> + mutex_unlock(&client->lock);
> if (data.fd.fd < 0)
> ret = data.fd.fd;
> break;
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-02-17 6:32 [RFC PATCH] staging/android/ion : fix a race condition in the ion driver EunTaik Lee
2016-02-17 18:54 ` Laura Abbott
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