From 236cf17c2502007a9d2dda3c39fb0d9a6bd03cc2 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 16 Feb 2016 14:47:31 +0000 Subject: [PATCH] KVM: arm/arm64: vgic: Ensure bitmaps are long enough 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: [] dump_backtrace+0x0/0x280 [] show_stack+0x14/0x20 [] dump_stack+0x100/0x188 [] print_trailer+0xfc/0x168 [] object_err+0x3c/0x50 [] kasan_report_error+0x244/0x558 [] __asan_report_load8_noabort+0x48/0x50 [] __bitmap_or+0xc0/0xc8 [] kvm_vgic_flush_hwstate+0x1bc/0x650 [] kvm_arch_vcpu_ioctl_run+0x2ec/0xa60 [] kvm_vcpu_ioctl+0x474/0xa68 [] do_vfs_ioctl+0x5b8/0xcb0 [] SyS_ioctl+0x8c/0xa0 [] 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@vger.kernel.org Acked-by: Marc Zyngier Acked-by: Christoffer Dall Signed-off-by: Mark Rutland Signed-off-by: Marc Zyngier --- 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 043032c6a5a4..00429b392c61 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); -- 2.39.5