[Qemu-devel] [PATCH] Fix an infinite loop in the emulated SB16 device

[Qemu-devel] [PATCH] Fix an infinite loop in the emulated SB16 device

[Aurelien Jarno]

This patch from Tavis Ormandy <taviso@google.com> fixes an infinite
loop in the emulated SB16 device.

See http://taviso.decsystem.org/virtsec.pdf for more details.
---
 hw/sb16.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/sb16.c b/hw/sb16.c
index c22de7a..b2a3a70 100644
--- a/hw/sb16.c
+++ b/hw/sb16.c
@@ -1246,8 +1246,10 @@ static int SB_read_DMA (void *opaque, int nchan, int dma_pos, int dma_len)
             s->block_size);
 #endif
 
-    while (s->left_till_irq <= 0) {
-        s->left_till_irq = s->block_size + s->left_till_irq;
+    if (s->block_size) {
+        while (s->left_till_irq <= 0) {
+            s->left_till_irq = s->block_size + s->left_till_irq;
+        }
     }
 
     return dma_pos;

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net

Re: [Qemu-devel] [PATCH] Fix an infinite loop in the emulated SB16 device

[malc]

On Mon, 28 Jan 2008, Aurelien Jarno wrote:

> This patch from Tavis Ormandy <taviso@google.com> fixes an infinite
> loop in the emulated SB16 device.
>
> See http://taviso.decsystem.org/virtsec.pdf for more details.
> ---
> hw/sb16.c |    6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/sb16.c b/hw/sb16.c
> index c22de7a..b2a3a70 100644
> --- a/hw/sb16.c
> +++ b/hw/sb16.c
> @@ -1246,8 +1246,10 @@ static int SB_read_DMA (void *opaque, int nchan, int dma_pos, int dma_len)
>             s->block_size);
> #endif
>
> -    while (s->left_till_irq <= 0) {
> -        s->left_till_irq = s->block_size + s->left_till_irq;
> +    if (s->block_size) {
> +        while (s->left_till_irq <= 0) {
> +            s->left_till_irq = s->block_size + s->left_till_irq;
> +        }
>     }
>
>     return dma_pos;

This was fixed by commit 'Mon Jan 14 04:24:29 2008 UTC (2 weeks, 1 day 
ago) by balrog', and the fix is elaborated on in:

http://lists.gnu.org/archive/html/qemu-devel/2007-05/msg00038.html
http://lists.gnu.org/archive/html/qemu-devel/2007-05/msg00019.html

-- 
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