919f4ebc59
Reported by syzkaller:
KASAN: null-ptr-deref in range [0x0000000000000140-0x0000000000000147]
CPU: 1 PID: 8370 Comm: syz-executor859 Not tainted 5.11.0-syzkaller #0
RIP: 0010:synic_get arch/x86/kvm/hyperv.c:165 [inline]
RIP: 0010:kvm_hv_set_sint_gsi arch/x86/kvm/hyperv.c:475 [inline]
RIP: 0010:kvm_hv_irq_routing_update+0x230/0x460 arch/x86/kvm/hyperv.c:498
Call Trace:
kvm_set_irq_routing+0x69b/0x940 arch/x86/kvm/../../../virt/kvm/irqchip.c:223
kvm_vm_ioctl+0x12d0/0x2800 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3959
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
Hyper-V context is lazily allocated until Hyper-V specific MSRs are accessed
or SynIC is enabled. However, the syzkaller testcase sets irq routing table
directly w/o enabling SynIC. This results in null-ptr-deref when accessing
SynIC Hyper-V context. This patch fixes it.
syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=163342ccd00000
Reported-by: syzbot+6987f3b2dbd9eda95f12@syzkaller.appspotmail.com
Fixes: 8f014550dfb1 ("KVM: x86: hyper-v: Make Hyper-V emulation enablement conditional")
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1614326399-5762-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.