From 94788af4ed039476ff3527b0e6a12c1dc42cb022 Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Sun, 9 Feb 2020 19:33:38 +0300 Subject: [PATCH] dmaengine: tegra-apb: Fix use-after-free I was doing some experiments with I2C and noticed that Tegra APB DMA driver crashes sometime after I2C DMA transfer termination. The crash happens because tegra_dma_terminate_all() bails out immediately if pending list is empty, and thus, it doesn't release the half-completed descriptors which are getting re-used before ISR tasklet kicks-in. tegra-i2c 7000c400.i2c: DMA transfer timeout elants_i2c 0-0010: elants_i2c_irq: failed to read data: -110 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 142 at lib/list_debug.c:45 __list_del_entry_valid+0x45/0xac list_del corruption, ddbaac44->next is LIST_POISON1 (00000100) Modules linked in: CPU: 0 PID: 142 Comm: kworker/0:2 Not tainted 5.5.0-rc2-next-20191220-00175-gc3605715758d-dirty #538 Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) Workqueue: events_freezable_power_ thermal_zone_device_check [] (unwind_backtrace) from [] (show_stack+0x11/0x14) [] (show_stack) from [] (dump_stack+0x85/0x94) [] (dump_stack) from [] (__warn+0xc1/0xc4) [] (__warn) from [] (warn_slowpath_fmt+0x61/0x78) [] (warn_slowpath_fmt) from [] (__list_del_entry_valid+0x45/0xac) [] (__list_del_entry_valid) from [] (tegra_dma_tasklet+0x5b/0x154) [] (tegra_dma_tasklet) from [] (tasklet_action_common.constprop.0+0x41/0x7c) [] (tasklet_action_common.constprop.0) from [] (__do_softirq+0xd3/0x2a8) [] (__do_softirq) from [] (irq_exit+0x7b/0x98) [] (irq_exit) from [] (__handle_domain_irq+0x45/0x80) [] (__handle_domain_irq) from [] (gic_handle_irq+0x45/0x7c) [] (gic_handle_irq) from [] (__irq_svc+0x65/0x94) Exception stack(0xde2ebb90 to 0xde2ebbd8) Signed-off-by: Dmitry Osipenko Acked-by: Jon Hunter Cc: Link: https://lore.kernel.org/r/20200209163356.6439-2-digetx@gmail.com Signed-off-by: Vinod Koul --- drivers/dma/tegra20-apb-dma.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c index 3a45079d11ec..319f31d27014 100644 --- a/drivers/dma/tegra20-apb-dma.c +++ b/drivers/dma/tegra20-apb-dma.c @@ -756,10 +756,6 @@ static int tegra_dma_terminate_all(struct dma_chan *dc) bool was_busy; spin_lock_irqsave(&tdc->lock, flags); - if (list_empty(&tdc->pending_sg_req)) { - spin_unlock_irqrestore(&tdc->lock, flags); - return 0; - } if (!tdc->busy) goto skip_dma_stop;