From: Mark Rutland <mark.rutland@xxxxxxx>
When we allocate bitmaps in vgic_vcpu_init_maps, we divide the number of
bits we need by 8 to figure out how many bytes to allocate. However,
bitmap elements are always accessed as unsigned longs, and if we didn't
happen to allocate a size such that size % sizeof(unsigned long) == 0,
bitmap accesses may go past the end of the allocation.
When using KASAN (which does byte-granular access checks), this results
in a continuous stream of BUGs whenever these bitmaps are accessed:
=============================================================================
BUG kmalloc-128 (Tainted: G B ): kasan: bad access detected
-----------------------------------------------------------------------------
INFO: Allocated in vgic_init.part.25+0x55c/0x990 age=7493 cpu=3 pid=1730
INFO: Slab 0xffffffbde6d5da40 objects=16 used=15 fp=0xffffffc935769700 flags=0x4000000000000080
INFO: Object 0xffffffc935769500 @offset=1280 fp=0x (null)
Bytes b4 ffffffc9357694f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Object ffffffc935769570: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Padding ffffffc9357695f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
CPU: 3 PID: 1740 Comm: kvm-vcpu-0 Tainted: G B 4.4.0+ #17
Hardware name: ARM Juno development board (r1) (DT)
Call trace:
[<ffffffc00008e770>] dump_backtrace+0x0/0x280
[<ffffffc00008ea04>] show_stack+0x14/0x20
[<ffffffc000726360>] dump_stack+0x100/0x188
[<ffffffc00030d324>] print_trailer+0xfc/0x168
[<ffffffc000312294>] object_err+0x3c/0x50
[<ffffffc0003140fc>] kasan_report_error+0x244/0x558
[<ffffffc000314548>] __asan_report_load8_noabort+0x48/0x50
[<ffffffc000745688>] __bitmap_or+0xc0/0xc8
[<ffffffc0000d9e44>] kvm_vgic_flush_hwstate+0x1bc/0x650
[<ffffffc0000c514c>] kvm_arch_vcpu_ioctl_run+0x2ec/0xa60
[<ffffffc0000b9a6c>] kvm_vcpu_ioctl+0x474/0xa68
[<ffffffc00036b7b0>] do_vfs_ioctl+0x5b8/0xcb0
[<ffffffc00036bf34>] SyS_ioctl+0x8c/0xa0
[<ffffffc000086cb0>] el0_svc_naked+0x24/0x28
Memory state around the buggy address:
ffffffc935769400: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffffc935769480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffffffc935769500: 04 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffffffc935769580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffffc935769600: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
Fix the issue by always allocating a multiple of sizeof(unsigned long),
as we do elsewhere in the vgic code.
Fixes: c1bfb577a ("arm/arm64: KVM: vgic: switch to dynamic allocation")
Cc: stable@xxxxxxxxxxxxxxx
Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
virt/kvm/arm/vgic.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 043032c..00429b3 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1875,8 +1875,8 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
-
- int sz = (nr_irqs - VGIC_NR_PRIVATE_IRQS) / 8;
+ int nr_longs = BITS_TO_LONGS(nr_irqs - VGIC_NR_PRIVATE_IRQS);
+ int sz = nr_longs * sizeof(unsigned long);
vgic_cpu->pending_shared = kzalloc(sz, GFP_KERNEL);
vgic_cpu->active_shared = kzalloc(sz, GFP_KERNEL);
vgic_cpu->pend_act_shared = kzalloc(sz, GFP_KERNEL);
--
2.1.4
--
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