From: "Jan Beulich" <JBeulich@novell.com>
To: <mingo@elte.hu>, <tglx@linutronix.de>, <hpa@zytor.com>
Cc: <stable@kernel.org>, "Roland McGrath" <roland@redhat.com>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH, resend] x86-64: fix register leak in 32-bit syscall audting
Date: Mon, 26 Oct 2009 15:20:29 +0000 [thread overview]
Message-ID: <4AE5CC4D020000780001BD13@vpn.id2.novell.com> (raw)
Restoring %ebp after the call to audit_syscall_exit() is not only
unnecessary (because the register didn't get clobbered), but in the
sysenter case wasn't even doing the right thing: It loaded %ebp from a
location below the top of stack (RBP < ARGOFFSET), i.e. arbitrary
kernel data got passed back to user mode in the register.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: <stable@kernel.org>
---
arch/x86/ia32/ia32entry.S | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- linux-2.6.32-rc5/arch/x86/ia32/ia32entry.S 2009-10-19 13:12:43.000000000 +0200
+++ 2.6.32-rc5-x86_64-ia32-syscall-audit-ebp/arch/x86/ia32/ia32entry.S 2009-10-19 09:36:39.000000000 +0200
@@ -204,7 +204,7 @@ sysexit_from_sys_call:
movl RDI-ARGOFFSET(%rsp),%r8d /* reload 5th syscall arg */
.endm
- .macro auditsys_exit exit,ebpsave=RBP
+ .macro auditsys_exit exit
testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)
jnz ia32_ret_from_sys_call
TRACE_IRQS_ON
@@ -217,7 +217,6 @@ sysexit_from_sys_call:
call audit_syscall_exit
GET_THREAD_INFO(%r10)
movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall return value */
- movl \ebpsave-ARGOFFSET(%rsp),%ebp /* reload user register value */
movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
cli
TRACE_IRQS_OFF
@@ -351,7 +350,7 @@ cstar_auditsys:
jmp cstar_dispatch
sysretl_audit:
- auditsys_exit sysretl_from_sys_call, RCX /* user %ebp in RCX slot */
+ auditsys_exit sysretl_from_sys_call
#endif
cstar_tracesys:
next reply other threads:[~2009-10-26 15:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-26 15:20 Jan Beulich [this message]
2009-10-26 15:24 ` [tip:x86/urgent] x86-64: Fix " tip-bot for Jan Beulich
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