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Subject[PATCH 5.4 18/71] dmaengine: mediatek: free the proper desc in desc_free handler
Date
From: Guillaume Ranquet <granquet@baylibre.com>

[ Upstream commit 0a2ff58f9f8f95526ecb0ccd7517fefceb96f661 ]

The desc_free handler assumed that the desc we want to free was always
the current one associated with the channel.

This is seldom the case and this is causing use after free crashes in
multiple places (tx/rx/terminate...).

BUG: KASAN: use-after-free in mtk_uart_apdma_rx_handler+0x120/0x304

Call trace:
dump_backtrace+0x0/0x1b0
show_stack+0x24/0x34
dump_stack+0xe0/0x150
print_address_description+0x8c/0x55c
__kasan_report+0x1b8/0x218
kasan_report+0x14/0x20
__asan_load4+0x98/0x9c
mtk_uart_apdma_rx_handler+0x120/0x304
mtk_uart_apdma_irq_handler+0x50/0x80
__handle_irq_event_percpu+0xe0/0x210
handle_irq_event+0x8c/0x184
handle_fasteoi_irq+0x1d8/0x3ac
__handle_domain_irq+0xb0/0x110
gic_handle_irq+0x50/0xb8
el0_irq_naked+0x60/0x6c

Allocated by task 3541:
__kasan_kmalloc+0xf0/0x1b0
kasan_kmalloc+0x10/0x1c
kmem_cache_alloc_trace+0x90/0x2dc
mtk_uart_apdma_prep_slave_sg+0x6c/0x1a0
mtk8250_dma_rx_complete+0x220/0x2e4
vchan_complete+0x290/0x340
tasklet_action_common+0x220/0x298
tasklet_action+0x28/0x34
__do_softirq+0x158/0x35c

Freed by task 3541:
__kasan_slab_free+0x154/0x224
kasan_slab_free+0x14/0x24
slab_free_freelist_hook+0xf8/0x15c
kfree+0xb4/0x278
mtk_uart_apdma_desc_free+0x34/0x44
vchan_complete+0x1bc/0x340
tasklet_action_common+0x220/0x298
tasklet_action+0x28/0x34
__do_softirq+0x158/0x35c

The buggy address belongs to the object at ffff000063606800
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 176 bytes inside of
256-byte region [ffff000063606800, ffff000063606900)
The buggy address belongs to the page:
page:fffffe00016d8180 refcount:1 mapcount:0 mapping:ffff00000302f600 index:0x0 compound_mapcount: 0
flags: 0xffff00000010200(slab|head)
raw: 0ffff00000010200 dead000000000100 dead000000000122 ffff00000302f600
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>

Link: https://lore.kernel.org/r/20210513192642.29446-2-granquet@baylibre.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/dma/mediatek/mtk-uart-apdma.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c b/drivers/dma/mediatek/mtk-uart-apdma.c
index f40051d6aecb..311d7c236d27 100644
--- a/drivers/dma/mediatek/mtk-uart-apdma.c
+++ b/drivers/dma/mediatek/mtk-uart-apdma.c
@@ -131,10 +131,7 @@ static unsigned int mtk_uart_apdma_read(struct mtk_chan *c, unsigned int reg)

static void mtk_uart_apdma_desc_free(struct virt_dma_desc *vd)
{
- struct dma_chan *chan = vd->tx.chan;
- struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
-
- kfree(c->desc);
+ kfree(container_of(vd, struct mtk_uart_apdma_desc, vd));
}

static void mtk_uart_apdma_start_tx(struct mtk_chan *c)
--
2.30.2
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