On Fri, Feb 1, 2019 at 7:49 AM Andrew Cooper <andrew.coop...@citrix.com> wrote:
>
> c/s 9338a37d "x86/svm: implement debug events" added support for introspecting
> ICEBP debug exceptions, but didn't account for the fact that
> svm_get_insn_len() (previously __get_instruction_length) can fail and may
> already raise #GP for the guest.
>
> If svm_get_insn_len() fails, return back to guest context rather than
> continuing and mistaking a trap-style VMExit for a fault-style one.
>
> Spotted by Coverity.
>
> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
> ---
> CC: Jan Beulich <jbeul...@suse.com>
> CC: Wei Liu <wei.l...@citrix.com>
> CC: Roger Pau Monné <roger....@citrix.com>
> CC: Boris Ostrovsky <boris.ostrov...@oracle.com>
> CC: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
> CC: Brian Woods <brian.wo...@amd.com>
> CC: Juergen Gross <jgr...@suse.com>
> CC: Razvan Cojocaru <rcojoc...@bitdefender.com>
> CC: Tamas K Lengyel <ta...@tklengyel.com>
>
> This wants backporting to Xen 4.11
> ---
> xen/arch/x86/hvm/svm/svm.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index 2584b90..e21091c 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -2758,6 +2758,9 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
> {
> trap_type = X86_EVENTTYPE_PRI_SW_EXCEPTION;
> inst_len = svm_get_insn_len(v, INSTR_ICEBP);
> +
> + if ( !instr_len )
Should that have been inst_len instead of instr_len?
Tamas
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