On 14/8/26 11:06, Peter Maydell wrote:
On Thu, 13 Aug 2026 at 08:24, Jamin Lin <[email protected]> wrote:
Coverity reports that ehci_writeback_async_complete_packet() ignores
the return value of get_dwords() when reading the QH and qTD.
Handle read failures in the same way as QH and qTD verification
failures by freeing the packet and returning early.
Signed-off-by: Jamin Lin <[email protected]>
---
hw/usb/hcd-ehci.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 451a918e9f..d43951975a 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -533,11 +533,11 @@ static void
ehci_writeback_async_complete_packet(EHCIPacket *p)
/* Verify the qh + qtd, like we do when going through fetchqh & fetchqtd
*/
memset(&qh, 0, sizeof(qh));
memset(&qtd, 0, sizeof(qtd));
- get_dwords(q->ehci, NLPTR_GET(q->qhaddr),
- (uint32_t *) &qh, ehci_qh_dwords(q->ehci));
- get_dwords(q->ehci, NLPTR_GET(q->qtdaddr),
- (uint32_t *) &qtd, ehci_qtd_dwords(q->ehci));
- if (!ehci_verify_qh(q, &qh) || !ehci_verify_qtd(p, &qtd)) {
+ if (get_dwords(q->ehci, NLPTR_GET(q->qhaddr),
+ (uint32_t *) &qh, ehci_qh_dwords(q->ehci)) < 0 ||
+ get_dwords(q->ehci, NLPTR_GET(q->qtdaddr),
+ (uint32_t *) &qtd, ehci_qtd_dwords(q->ehci)) < 0 ||
+ !ehci_verify_qh(q, &qh) || !ehci_verify_qtd(p, &qtd)) {
p->async = EHCI_ASYNC_INITIALIZED;
ehci_free_packet(p);
return;
Looking at the coverity report, my question is whether echi->as
can ever actually be NULL. This is the address space we use to
do DMA, so it feels like every EHCI device must set that up
somehow. ehci_sysbus_init() does. So does usb_ehci_pci_realize().
usb_ehci_pci_write_config() can change it, but never to NULL.
If echi->as is always non-NULL then we could change get_dwords()
and put_dwords() to return "void".
Alternatively, maybe get_dwords() and put_dwords() should be
checking the return value from dma_memory_write() and
dma_memory_read() so that they fail if the DMA fails...
Oh good point, I missed that. We really should qualify
dma_memory_write() & co with G_GNUC_WARN_UNUSED_RESULT, that'd
help us preventing such mistakes.
