From d695c12c57feae371c943e019af920bc8b732dfb Mon Sep 17 00:00:00 2001 From: Shuah Khan Date: Fri, 8 Jul 2016 19:29:25 -0300 Subject: [PATCH] [media] 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 : [] lr : [] psr: 60010013 odroid kernel: [] (s5p_mfc_reset [s5p_mfc]) from [] (s5p_mfc_deinit_hw+0x14/0x3c [s5p_mfc]) odroid kernel: [] (s5p_mfc_deinit_hw [s5p_mfc]) from [] (s5p_mfc_release+0xac/0x1c4 [s5p_mfc]) odroid kernel: [] (s5p_mfc_release [s5p_mfc]) from [] (v4l2_release+0x38/0x74 [videodev]) odroid kernel: [] (v4l2_release [videodev]) from [] (__fput+0x80/0x1c8) odroid kernel: [] (__fput) from [] (task_work_run+0x94/0xc8) odroid kernel: [] (task_work_run) from [] (do_work_pending+0x7c/0xa4) odroid kernel: [] (do_work_pending) from [] (slow_work_pending+0xc/0x20) odroid kernel: Code: eb3edacc e5953078 e3a06000 e2833c11 (e5836004) Signed-off-by: Shuah Khan Tested-by: Luis de Bethencourt Signed-off-by: Sylwester Nawrocki Signed-off-by: Mauro Carvalho Chehab --- 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 e3f104fafd0a..69c91c01b997 100644 --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c @@ -924,39 +924,50 @@ 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; } @@ -1298,9 +1309,26 @@ static int s5p_mfc_probe(struct platform_device *pdev) 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); -- GitLab