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Date: Fri, 8 Jul 2016 16:29:25 -0600
From: Shuah Khan <shuahkh@....samsung.com>
To: kyungmin.park@...sung.com, k.debski@...sung.com,
jtp.park@...sung.com, mchehab@...nel.org, javier@....samsung.com
Cc: Shuah Khan <shuahkh@....samsung.com>,
linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org, luisbg@....samsung.com
Subject: [PATCH] media: s5p-mfc fix invalid memory access from s5p_mfc_release()
If s5p_mfc_release() runs after s5p_mfc_remove(), the former will access
invalid s5p_mfc_dev pointer saved in the s5p_mfc_ctx and runs into kernel
paging request errors.
Clear ctx dev pointer in s5p_mfc_remove() and change s5p_mfc_release() to
avoid work that requires ctx->dev.
odroid kernel: Unable to handle kernel paging request at virtual address
f17c1104
odroid kernel: pgd = ebca4000
odroid kernel: [f17c1104] *pgd=6e23d811, *pte=00000000, *ppte=00000000
odroid kernel: Internal error: Oops: 807 [#1] PREEMPT SMP ARM
odroid kernel: Modules linked in: cpufreq_userspace cpufreq_powersave
cpufreq_conservative s5p_mfc s5p_jpeg v4l2_mem2mem
videobuf2_dma_contig videobuf2_memops videobuf2_v4l2 videobuf2_core
v4l2_common videodev media
odroid kernel: Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
odroid kernel: task: c2241400 ti: e7018000 task.ti: e7018000
odroid kernel: PC is at s5p_mfc_reset+0x40/0x28c [s5p_mfc]
odroid kernel: LR is at s5p_mfc_reset+0x34/0x28c [s5p_mfc]
odroid kernel: pc : [<bf15bfbc>] lr : [<bf15bfb0>] psr: 60010013
odroid kernel: [<bf15bfbc>] (s5p_mfc_reset [s5p_mfc]) from [<bf15c62c>]
(s5p_mfc_deinit_hw+0x14/0x3c [s5p_mfc])
odroid kernel: [<bf15c62c>] (s5p_mfc_deinit_hw [s5p_mfc]) from [<bf155958>]
(s5p_mfc_release+0xac/0x1c4 [s5p_mfc])
odroid kernel: [<bf155958>] (s5p_mfc_release [s5p_mfc]) from [<bf021344>]
(v4l2_release+0x38/0x74 [videodev])
odroid kernel: [<bf021344>] (v4l2_release [videodev]) from [<c01e4274>]
(__fput+0x80/0x1c8)
odroid kernel: [<c01e4274>] (__fput) from [<c0135c58>]
(task_work_run+0x94/0xc8)
odroid kernel: [<c0135c58>] (task_work_run) from [<c010a9d4>]
(do_work_pending+0x7c/0xa4)
odroid kernel: [<c010a9d4>] (do_work_pending) from [<c0107794>]
(slow_work_pending+0xc/0x20)
odroid kernel: Code: eb3edacc e5953078 e3a06000 e2833c11 (e5836004)
Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
---
drivers/media/platform/s5p-mfc/s5p_mfc.c | 72 ++++++++++++++++++++++----------
1 file changed, 50 insertions(+), 22 deletions(-)
diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c
index f537b74..c96421f 100644
--- a/drivers/media/platform/s5p-mfc/s5p_mfc.c
+++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c
@@ -925,39 +925,50 @@ static int s5p_mfc_release(struct file *file)
struct s5p_mfc_ctx *ctx = fh_to_ctx(file->private_data);
struct s5p_mfc_dev *dev = ctx->dev;
+ /* if dev is null, do cleanup that doesn't need dev */
mfc_debug_enter();
- mutex_lock(&dev->mfc_mutex);
+ if (dev)
+ mutex_lock(&dev->mfc_mutex);
s5p_mfc_clock_on();
vb2_queue_release(&ctx->vq_src);
vb2_queue_release(&ctx->vq_dst);
- /* Mark context as idle */
- clear_work_bit_irqsave(ctx);
- /* If instance was initialised and not yet freed,
- * return instance and free resources */
- if (ctx->state != MFCINST_FREE && ctx->state != MFCINST_INIT) {
- mfc_debug(2, "Has to free instance\n");
- s5p_mfc_close_mfc_inst(dev, ctx);
- }
- /* hardware locking scheme */
- if (dev->curr_ctx == ctx->num)
- clear_bit(0, &dev->hw_lock);
- dev->num_inst--;
- if (dev->num_inst == 0) {
- mfc_debug(2, "Last instance\n");
- s5p_mfc_deinit_hw(dev);
- del_timer_sync(&dev->watchdog_timer);
- if (s5p_mfc_power_off() < 0)
- mfc_err("Power off failed\n");
+ if (dev) {
+ /* Mark context as idle */
+ clear_work_bit_irqsave(ctx);
+ /*
+ * If instance was initialised and not yet freed,
+ * return instance and free resources
+ */
+ if (ctx->state != MFCINST_FREE && ctx->state != MFCINST_INIT) {
+ mfc_debug(2, "Has to free instance\n");
+ s5p_mfc_close_mfc_inst(dev, ctx);
+ }
+ /* hardware locking scheme */
+ if (dev->curr_ctx == ctx->num)
+ clear_bit(0, &dev->hw_lock);
+ dev->num_inst--;
+ if (dev->num_inst == 0) {
+ mfc_debug(2, "Last instance\n");
+ s5p_mfc_deinit_hw(dev);
+ del_timer_sync(&dev->watchdog_timer);
+ if (s5p_mfc_power_off() < 0)
+ mfc_err("Power off failed\n");
+ }
}
mfc_debug(2, "Shutting down clock\n");
s5p_mfc_clock_off();
- dev->ctx[ctx->num] = NULL;
+ if (dev)
+ dev->ctx[ctx->num] = NULL;
s5p_mfc_dec_ctrls_delete(ctx);
v4l2_fh_del(&ctx->fh);
- v4l2_fh_exit(&ctx->fh);
+ /* vdev is gone if dev is null */
+ if (dev)
+ v4l2_fh_exit(&ctx->fh);
kfree(ctx);
mfc_debug_leave();
- mutex_unlock(&dev->mfc_mutex);
+ if (dev)
+ mutex_unlock(&dev->mfc_mutex);
+
return 0;
}
@@ -1309,9 +1320,26 @@ err_res:
static int s5p_mfc_remove(struct platform_device *pdev)
{
struct s5p_mfc_dev *dev = platform_get_drvdata(pdev);
+ struct s5p_mfc_ctx *ctx;
+ int i;
v4l2_info(&dev->v4l2_dev, "Removing %s\n", pdev->name);
+ /*
+ * Clear ctx dev pointer to avoid races between s5p_mfc_remove()
+ * and s5p_mfc_release() and s5p_mfc_release() accessing ctx->dev
+ * after s5p_mfc_remove() is run during unbind.
+ */
+ mutex_lock(&dev->mfc_mutex);
+ for (i = 0; i < MFC_NUM_CONTEXTS; i++) {
+ ctx = dev->ctx[i];
+ if (!ctx)
+ continue;
+ /* clear ctx->dev */
+ ctx->dev = NULL;
+ }
+ mutex_unlock(&dev->mfc_mutex);
+
del_timer_sync(&dev->watchdog_timer);
flush_workqueue(dev->watchdog_workqueue);
destroy_workqueue(dev->watchdog_workqueue);
--
2.7.4
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