From: Andy Lutomirski Date: Tue, 4 Nov 2014 23:36:50 +0000 (-0800) Subject: x86_64/vsyscall: Restore orig_ax after vsyscall seccomp X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=26893107aa717cd11010f0c278d02535defa1ac9;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git x86_64/vsyscall: Restore orig_ax after vsyscall seccomp The vsyscall emulation code sets orig_ax for seccomp's benefit, but it forgot to set it back. I'm not sure that this is observable at all, but it could cause confusion to various /proc or ptrace users, and it's possible that it could cause minor artifacts if a signal were to be delivered on return from vsyscall emulation. Signed-off-by: Andy Lutomirski Cc: Linus Torvalds Link: http://lkml.kernel.org/r/cdc6a564517a4df09235572ee5f530ccdcf933f7.1415144089.git.luto@amacapital.net Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c index 7d9eb4bc10ac..2dcc6ff6fdcc 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -206,6 +206,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) "seccomp tried to change syscall nr or ip"); do_exit(SIGSYS); } + regs->orig_ax = -1; if (tmp) goto do_ret; /* skip requested */