Tim Gardner
2013-Feb-08 20:34 UTC
[PATCH linux-next] xen/multicall: xen_mc_callback(): avoid buffer overflow
This buffer overflow was introduced with
91e0c5f3dad47838cb2ecc1865ce789a0b7182b1
(2.6.24).
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Jeremy Fitzhardinge <jeremy at goop.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: x86 at kernel.org
Cc: xen-devel at lists.xensource.com
Cc: virtualization at lists.linux-foundation.org
Cc: stable at vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
This patch applies cleanly to 3.1.10 and newer. Requires a backport
for 2.6.24-3.2.y
arch/x86/xen/multicalls.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 0d82003..5270407 100644
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -195,9 +195,10 @@ void xen_mc_callback(void (*fn)(void *), void *data)
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
struct callback *cb;
- if (b->cbidx == MC_BATCH) {
+ if (b->cbidx >= MC_BATCH) {
trace_xen_mc_flush_reason(XEN_MC_FL_CALLBACK);
xen_mc_flush();
+ return;
}
trace_xen_mc_callback(fn, data);
--
1.7.9.5
David Vrabel
2013-Feb-08 21:13 UTC
[Xen-devel] [PATCH linux-next] xen/multicall: xen_mc_callback(): avoid buffer overflow
On 08/02/2013 20:34, Tim Gardner wrote:> This buffer overflow was introduced with 91e0c5f3dad47838cb2ecc1865ce789a0b7182b1 > (2.6.24).There's no buffer overflow here. xen_mc_flush() resets b->cbidx. David> arch/x86/xen/multicalls.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c > index 0d82003..5270407 100644 > --- a/arch/x86/xen/multicalls.c > +++ b/arch/x86/xen/multicalls.c > @@ -195,9 +195,10 @@ void xen_mc_callback(void (*fn)(void *), void *data) > struct mc_buffer *b = &__get_cpu_var(mc_buffer); > struct callback *cb; > > - if (b->cbidx == MC_BATCH) { > + if (b->cbidx >= MC_BATCH) { > trace_xen_mc_flush_reason(XEN_MC_FL_CALLBACK); > xen_mc_flush(); > + return; > } > > trace_xen_mc_callback(fn, data); >