• Dominik Brodowski's avatar
    syscalls/x86: Extend register clearing on syscall entry to lower registers · 6dc936f1
    Dominik Brodowski authored
    To reduce the chance that random user space content leaks down the call
    chain in registers, also clear lower registers on syscall entry:
    
    For 64-bit syscalls, extend the register clearing in PUSH_AND_CLEAR_REGS
    to %dx and %cx. This should not hurt at all, also on the other callers
    of that macro. We do not need to clear %rdi and %rsi for syscall entry,
    as those registers are used to pass the parameters to do_syscall_64().
    
    For the 32-bit compat syscalls, do_int80_syscall_32() and
    do_fast_syscall_32() each only take one parameter. Therefore, extend the
    register clearing to %dx, %cx, and %si in entry_SYSCALL_compat and
    entry_INT80_compat.
    Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
    Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/20180405095307.3730-8-linux@dominikbrodowski.netSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    6dc936f1
entry_64_compat.S 13.4 KB