+-- On Sun, 31 Jan 2021, Philippe Mathieu-Daudé wrote --+
| On 1/31/21 11:34 AM, Philippe Mathieu-Daudé wrote:
| > Per the ARM Generic Interrupt Controller Architecture specification
| > (document "ARM IHI 0048B.b (ID072613)"), the SGIINTID field is 4 bit,
| > not 10:
| >
| > - Table 4-21 GICD_SGIR bit assignments
| >
| > The Interrupt ID of the SGI to forward to the specified CPU
| > interfaces. The value of this field is the Interrupt ID, in
| > the range 0-15, for example a value of 0b0011 specifies
| > Interrupt ID 3.
| >
| > diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
| > index af41e2fb448..75316329516 100644
| > --- a/hw/intc/arm_gic.c
| > +++ b/hw/intc/arm_gic.c
| > @@ -1476,7 +1476,7 @@ static void gic_dist_writel(void *opaque, hwaddr
offset,
| > int target_cpu;
| >
| > cpu = gic_get_current_cpu(s);
| > - irq = value & 0x3ff;
| > + irq = value & 0xf;
| > switch ((value >> 24) & 3) {
| > case 0:
| > mask = (value >> 16) & ALL_CPU_MASK;
| >
* Looks okay.
| > Correct the irq mask to fix an undefined behavior (which eventually
| > lead to a heap-buffer-overflow, see [Buglink]):
| >
| > $ echo 'writel 0x8000f00 0xff4affb0' | qemu-system-aarch64 -M
virt,accel=qtest -qtest stdio
| > [I 1612088147.116987] OPENED
| > [R +0.278293] writel 0x8000f00 0xff4affb0
| > ../hw/intc/arm_gic.c:1498:13: runtime error: index 944 out of bounds for
type 'uint8_t [16][8]'
| > SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
../hw/intc/arm_gic.c:1498:13
| >
| > Cc: qemu-sta...@nongnu.org
| > Fixes: 9ee6e8bb853 ("ARMv7 support.")
| > Buglink: https://bugs.launchpad.net/qemu/+bug/1913916
| > Buglink: https://bugs.launchpad.net/qemu/+bug/1913917
|
| > ---
| > Isnt it worth a CVE to help distributions track backports?
| > ---
* Please send such report(s) to 'qemu-security' list to be triaged as
potential security ones.
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D
