Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs

Mickaël Salaün
2015-12-21T09:12:58Z

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On 21/12/2015 01:20, Richard Weinberger wrote:
> Am 21.12.2015 um 01:03 schrieb Mickaël Salaün:
>> diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
>> index 1683b8e..65f0d1a 100644
>> --- a/arch/um/kernel/skas/syscall.c
>> +++ b/arch/um/kernel/skas/syscall.c
>> @@ -7,6 +7,7 @@
>> #include <linux/ptrace.h>
>> #include <kern_util.h>
>> #include <sysdep/ptrace.h>
>> +#include <sysdep/ptrace_user.h>
>> #include <sysdep/syscalls.h>
>> #include <os.h>
>>
>> @@ -16,12 +17,16 @@ void handle_syscall(struct uml_pt_regs *r)
>> long result;
>> int syscall;
>>
>> + /* Save the syscall register. */
>> + UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
>> +
>> if (syscall_trace_enter(regs)) {
>> result = -ENOSYS;
>> goto out;
>> }
>>
>> - syscall = get_syscall(r);
>> + /* Get the syscall after being potentially updated with ptrace. */
>> + syscall = UPT_SYSCALL_NR(r);
>
> Doesn't this break the support for changing syscall numbers using PTRACE_SETREGS?

The logic is unchanged except updating the UPT_SYSCALL_NR before syscall_trace_enter(). I did my last tests with the x86_32 subarchitecture and all tests (from selftest/seccomp), including PTRACE_SETREGS for syscall numbers tests, passed. However, 2 of this tests still fail for x86_64 (only).

Regards,
Mickaël

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