diff options
| author | Guodong Xu <guodong@riscstar.com> | 2025-12-16 17:10:06 +0300 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2025-12-16 17:58:39 +0300 |
| commit | a143545855bc2c6e1330f6f57ae375ac44af00a7 (patch) | |
| tree | 94f36fc0a06bc6f99e7835acca7a9675a003d79a | |
| parent | 430f7803b69cd5e5694e5dfc884c6628870af36e (diff) | |
| download | linux-a143545855bc2c6e1330f6f57ae375ac44af00a7.tar.xz | |
dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue()
Add proper locking in mmp_pdma_residue() to prevent use-after-free when
accessing descriptor list and descriptor contents.
The race occurs when multiple threads call tx_status() while the tasklet
on another CPU is freeing completed descriptors:
CPU 0 CPU 1
----- -----
mmp_pdma_tx_status()
mmp_pdma_residue()
-> NO LOCK held
list_for_each_entry(sw, ..)
DMA interrupt
dma_do_tasklet()
-> spin_lock(&desc_lock)
list_move(sw->node, ...)
spin_unlock(&desc_lock)
| dma_pool_free(sw) <- FREED!
-> access sw->desc <- UAF!
This issue can be reproduced when running dmatest on the same channel with
multiple threads (threads_per_chan > 1).
Fix by protecting the chain_running list iteration and descriptor access
with the chan->desc_lock spinlock.
Signed-off-by: Juan Li <lijuan@linux.spacemit.com>
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Link: https://patch.msgid.link/20251216-mmp-pdma-race-v1-1-976a224bb622@riscstar.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
| -rw-r--r-- | drivers/dma/mmp_pdma.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c index 86661eb3cde1..d12e729ee12c 100644 --- a/drivers/dma/mmp_pdma.c +++ b/drivers/dma/mmp_pdma.c @@ -928,6 +928,7 @@ static unsigned int mmp_pdma_residue(struct mmp_pdma_chan *chan, { struct mmp_pdma_desc_sw *sw; struct mmp_pdma_device *pdev = to_mmp_pdma_dev(chan->chan.device); + unsigned long flags; u64 curr; u32 residue = 0; bool passed = false; @@ -945,6 +946,8 @@ static unsigned int mmp_pdma_residue(struct mmp_pdma_chan *chan, else curr = pdev->ops->read_src_addr(chan->phy); + spin_lock_irqsave(&chan->desc_lock, flags); + list_for_each_entry(sw, &chan->chain_running, node) { u64 start, end; u32 len; @@ -989,6 +992,7 @@ static unsigned int mmp_pdma_residue(struct mmp_pdma_chan *chan, continue; if (sw->async_tx.cookie == cookie) { + spin_unlock_irqrestore(&chan->desc_lock, flags); return residue; } else { residue = 0; @@ -996,6 +1000,8 @@ static unsigned int mmp_pdma_residue(struct mmp_pdma_chan *chan, } } + spin_unlock_irqrestore(&chan->desc_lock, flags); + /* We should only get here in case of cyclic transactions */ return residue; } |