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[Qemu-block] [PATCH for-3.1] fdc: fix segfault in fdctrl_stop_transfer()
From: |
Mark Cave-Ayland |
Subject: |
[Qemu-block] [PATCH for-3.1] fdc: fix segfault in fdctrl_stop_transfer() when DMA is disabled |
Date: |
Sun, 11 Nov 2018 09:40:23 +0000 |
Commit c8a35f1cf0f "fdc: use IsaDma interface instead of global DMA_*
functions" accidentally introduced a segfault in fdctrl_stop_transfer() for
non-DMA transfers.
If fdctrl->dma_chann has not been configured then the fdctrl->dma interface
reference isn't initialised during isabus_fdc_realize(). Unfortunately
fdctrl_stop_transfer() unconditionally references the DMA interface when
finishing the transfer causing a NULL pointer dereference.
Fix the issue by adding a check in fdctrl_stop_transfer() so that the DMA
interface reference and release method is only invoked if fdctrl->dma_chann
has been set.
(This issue was discovered by Martin testing a recent change in the NetBSD
installer under qemu-system-sparc)
Reported-by: Martin Husemann <address@hidden>
Signed-off-by: Mark Cave-Ayland <address@hidden>
---
hw/block/fdc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 2e9c1e1e2f..6f19f127a5 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1617,7 +1617,7 @@ static void fdctrl_stop_transfer(FDCtrl *fdctrl, uint8_t
status0,
fdctrl->fifo[5] = cur_drv->sect;
fdctrl->fifo[6] = FD_SECTOR_SC;
fdctrl->data_dir = FD_DIR_READ;
- if (!(fdctrl->msr & FD_MSR_NONDMA)) {
+ if (fdctrl->dma_chann != -1 && !(fdctrl->msr & FD_MSR_NONDMA)) {
IsaDmaClass *k = ISADMA_GET_CLASS(fdctrl->dma);
k->release_DREQ(fdctrl->dma, fdctrl->dma_chann);
}
--
2.11.0
- [Qemu-block] [PATCH for-3.1] fdc: fix segfault in fdctrl_stop_transfer() when DMA is disabled,
Mark Cave-Ayland <=