From 0327559151c6886814d6d5b373b4bf6de63fb9f6 Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Wed, 21 Jul 2010 17:44:12 -0700 Subject: [PATCH] x86: auditsyscall: fix fastpath return value after reschedule In the CONFIG_AUDITSYSCALL fast-path for x86 64-bit system calls, we can pass a bad return value and/or error indication for the system call to audit_syscall_exit(). This happens when TIF_NEED_RESCHED was set as the system call returned, so we went out to schedule() and came back to the exit-audit fast-path. The fix is to reload the user return value register from the pt_regs before using it for audit_syscall_exit(). Both the 32-bit kernel's fast path and the 64-bit kernel's 32-bit system call fast paths work slightly differently, so that they always leave the fast path entirely to reschedule and don't return there, so they don't have the analogous bugs. Reported-by: Alexander Viro Signed-off-by: Roland McGrath --- arch/x86/kernel/entry_64.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 0697ff139837..4db7c4d12ffa 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -571,8 +571,8 @@ auditsys: * masked off. */ sysret_audit: - movq %rax,%rsi /* second arg, syscall return value */ - cmpq $0,%rax /* is it < 0? */ + movq RAX-ARGOFFSET(%rsp),%rsi /* second arg, syscall return value */ + cmpq $0,%rsi /* is it < 0? */ setl %al /* 1 if so, 0 if not */ movzbl %al,%edi /* zero-extend that into %edi */ inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */