On Mon, Jun 16, 2014 at 2:48 PM, H. Peter Anvin <h...@zytor.com> wrote: > On 06/16/2014 02:35 PM, Andy Lutomirski wrote: >> >> To hpa, etc: It appears that entry_32.S is missing any call to the >> audit exit hook on the badsys path. If I'm diagnosing this bug report >> correctly, this causes OOPSes. >> >> The the world at large: it's increasingly apparent that no one (except >> maybe the blackhats) has ever scrutinized the syscall auditing code. >> This is two old severe bugs in the code that have probably been there >> for a long time. >> > > Yes, the audit code is a total mess. > >> The bad syscall nr paths are their own incomprehensible route >> through the entry control flow. Rearrange them to work just like >> syscalls that return -ENOSYS. > > I have to admit... it sort of lends itself to a solution like this: > > /* For the 64-bit case, analogous code for 32 bits */ > movl $__NR_syscall_max+1,%ecx # *Not* __NR_syscall_max > cmpq %rcx,%rax > cmovae %rcx,%rax > movq %r10,%rcx > call *sys_call_table(,%rax,8) > > ... and having an extra (invalid) system call slot in the syscall table > beyond the end instead of branching off separately. > > (Note: we could use either cmova or cmovae, and either the 32- or 64-bit > form... the reason why is left as an exercise to the reader.)
This is CVE-2014-4508, and it's probably worth fixing. Is my patch good? I can resent and cc stable if needed. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
