Marc Zyngier <maz@xxxxxxxxxx> writes:
On 2022-06-30 17:50, Schspa Shi wrote:
Marc Zyngier <maz@xxxxxxxxxx> writes:
On Thu, 30 Jun 2022 17:12:20 +0100,
Schspa Shi <schspa@xxxxxxxxx> wrote:
If the len is 8 bytes, we can't get the correct sign extend
for
be system.
I'm afraid you'll have to give me a bit more details.
Fix the mask type len and the comparison of length.
Signed-off-by: Schspa Shi <schspa@xxxxxxxxx>
---
arch/arm64/kvm/mmio.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
index 3dd38a151d2a6..0692f8b18f35c 100644
--- a/arch/arm64/kvm/mmio.c
+++ b/arch/arm64/kvm/mmio.c
@@ -81,8 +81,8 @@ unsigned long kvm_mmio_read_buf(const void
*buf, unsigned
int len)
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
{
unsigned long data;
+ unsigned long mask;
unsigned int len;
- int mask;
/* Detect an already handled MMIO return */
if (unlikely(!vcpu->mmio_needed))
@@ -97,7 +97,7 @@ int kvm_handle_mmio_return(struct kvm_vcpu
*vcpu)
data = kvm_mmio_read_buf(run->mmio.data, len);
if (kvm_vcpu_dabt_issext(vcpu) &&
- len < sizeof(unsigned long)) {
+ len <= sizeof(unsigned long)) {
If you're reading an 8 byte quantity, what is there to
sign-extend?
Sign extension only makes sense if what you're reading is
*smaller*
than the size of the register you are targeting.
Yes, you are correct, sorry for my bad patch.
Please ignore this patch.
I must be missing something. And how is that related to
running BE? BE
in the host? The guest?
I mean BE is for guest running with BE mode.
So what problem did you see? If you have noticed something going
wrong, I'd like to get it fixed.
I have running some static code analysis software upon Kernel
code.
Seeing there is possible overflow.
maks << 1U << ((len * 8) -1);
The AI don't know, len is only the value of 1, 2, 4, and make this
a warnings
I tring to analysis this, but didn't realize the real scenario of
sign extension, and finally sent this problematic patch.
I do see some uninitialized memory reads (the values are not used
in the end, just as temporary space for API execution),
do we need to fix these?
Thanks,
M.
--
Schspa Shi
BRs
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