hw/pl011.c: Avoid crash on read when no chr backend present

Submitted by Peter Maydell on July 9, 2012, 2:27 p.m.

Details

Message ID 1341844029-28831-1-git-send-email-peter.maydell@linaro.org
State New
Headers show

Commit Message

Peter Maydell July 9, 2012, 2:27 p.m.
Add a missing guard that meant we would segfault if the guest read
UARTDR on a PL011 serial device which had no chr backend connected.
(This didn't happen for Linux guests because Linux reads the flags
register and doesn't try to read the UART if it's empty.)

Reported-by: Christian Müller <christian.mueller@heig-vd.ch>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/pl011.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

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diff --git a/hw/pl011.c b/hw/pl011.c
index 8a5a8f5..3245702 100644
--- a/hw/pl011.c
+++ b/hw/pl011.c
@@ -78,7 +78,9 @@  static uint64_t pl011_read(void *opaque, target_phys_addr_t offset,
         if (s->read_count == s->read_trigger - 1)
             s->int_level &= ~ PL011_INT_RX;
         pl011_update(s);
-        qemu_chr_accept_input(s->chr);
+        if (s->chr) {
+            qemu_chr_accept_input(s->chr);
+        }
         return c;
     case 1: /* UARTCR */
         return 0;