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media: coda: fix memory corruption in case more than 32 instances are opened

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The ffz() return value is undefined if the instance mask does not
contain any zeros. If it returned 32, the following set_bit would
corrupt the debugfs_root pointer.
Switch to IDA for context index allocation. This also removes the
artificial 32 instance limit for all except CodaDx6.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Philipp Zabel 2018-11-06 05:40:54 -05:00 committed by Mauro Carvalho Chehab
parent c45fbdf24c
commit 649cfc2bdf
2 changed files with 12 additions and 17 deletions
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26
drivers/media/platform/coda/coda-common.c
View File

@ -17,6 +17,7 @@
#include <linux/firmware.h>
#include <linux/gcd.h>
#include <linux/genalloc.h>
#include <linux/idr.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
@ -2099,17 +2100,6 @@ int coda_decoder_queue_init(void *priv, struct vb2_queue *src_vq,
return coda_queue_init(priv, dst_vq);
}
static int coda_next_free_instance(struct coda_dev *dev)
{
int idx = ffz(dev->instance_mask);
if ((idx < 0) ||
(dev->devtype->product == CODA_DX6 && idx > CODADX6_MAX_INSTANCES))
return -EBUSY;
return idx;
}
/*
* File operations
*/
@ -2118,7 +2108,8 @@ static int coda_open(struct file *file)
{
struct video_device *vdev = video_devdata(file);
struct coda_dev *dev = video_get_drvdata(vdev);
struct coda_ctx *ctx = NULL;
struct coda_ctx *ctx;
unsigned int max = ~0;
char *name;
int ret;
int idx;
@ -2127,12 +2118,13 @@ static int coda_open(struct file *file)
if (!ctx)
return -ENOMEM;
idx = coda_next_free_instance(dev);
if (dev->devtype->product == CODA_DX6)
max = CODADX6_MAX_INSTANCES - 1;
idx = ida_alloc_max(&dev->ida, max, GFP_KERNEL);
if (idx < 0) {
ret = idx;
goto err_coda_max;
}
set_bit(idx, &dev->instance_mask);
name = kasprintf(GFP_KERNEL, "context%d", idx);
if (!name) {
@ -2241,8 +2233,8 @@ err_clk_per:
err_pm_get:
v4l2_fh_del(&ctx->fh);
v4l2_fh_exit(&ctx->fh);
clear_bit(ctx->idx, &dev->instance_mask);
err_coda_name_init:
ida_free(&dev->ida, ctx->idx);
err_coda_max:
kfree(ctx);
return ret;
@ -2284,7 +2276,7 @@ static int coda_release(struct file *file)
pm_runtime_put_sync(&dev->plat_dev->dev);
v4l2_fh_del(&ctx->fh);
v4l2_fh_exit(&ctx->fh);
clear_bit(ctx->idx, &dev->instance_mask);
ida_free(&dev->ida, ctx->idx);
if (ctx->ops->release)
ctx->ops->release(ctx);
debugfs_remove_recursive(ctx->debugfs_entry);
@ -2745,6 +2737,7 @@ static int coda_probe(struct platform_device *pdev)
mutex_init(&dev->dev_mutex);
mutex_init(&dev->coda_mutex);
ida_init(&dev->ida);
dev->debugfs_root = debugfs_create_dir("coda", NULL);
if (!dev->debugfs_root)
@ -2832,6 +2825,7 @@ static int coda_remove(struct platform_device *pdev)
coda_free_aux_buf(dev, &dev->tempbuf);
coda_free_aux_buf(dev, &dev->workbuf);
debugfs_remove_recursive(dev->debugfs_root);
ida_destroy(&dev->ida);
return 0;
}

3
drivers/media/platform/coda/coda.h
View File

@ -16,6 +16,7 @@
#define __CODA_H__
#include <linux/debugfs.h>
#include <linux/idr.h>
#include <linux/irqreturn.h>
#include <linux/mutex.h>
#include <linux/kfifo.h>
@ -95,7 +96,7 @@ struct coda_dev {
struct workqueue_struct *workqueue;
struct v4l2_m2m_dev *m2m_dev;
struct list_head instances;
unsigned long instance_mask;
struct ida ida;
struct dentry *debugfs_root;
};