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authorMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>2018-11-11 09:40:23 +0000
committerKevin Wolf <kwolf@redhat.com>2018-11-19 12:51:22 +0100
commit441f6692ecc14859b77af2ac6d8f55e6f1354d3b (patch)
treeb85ca63dbe2421608c99188560f23dcdfa5bdfaa /hw/block
parent5e3c0220d7e4f0361c4d36c697a8842f2b583402 (diff)
fdc: fix segfault in fdctrl_stop_transfer() when DMA is disabled
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) Cc: qemu-stable@nongnu.org Reported-by: Martin Husemann <martin@duskware.de> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Hervé Poussineau <hpoussin@reactos.org> Reviewed-by: John Snow <jsnow@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'hw/block')
-rw-r--r--hw/block/fdc.c2
1 files changed, 1 insertions, 1 deletions
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);
}