Patchwork [01/10] hw/pl011.c: Avoid crash on read when no chr backend present

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Submitter Peter Maydell
Date July 20, 2012, 3 p.m.
Message ID <1342796430-16636-2-git-send-email-peter.maydell@linaro.org>
Download mbox | patch
Permalink /patch/172290/
State New
Headers show

Comments

Peter Maydell - July 20, 2012, 3 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(-)

Patch

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;