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Message-Id: <20141116215328.693816276@1wt.eu>
Date: Sun, 16 Nov 2014 22:53:29 +0100
From: Willy Tarreau <w@....eu>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Roland McGrath <roland@...hat.com>,
Andy Lutomirski <luto@...capital.net>,
"H. Peter Anvin" <hpa@...ux.intel.com>, Willy Tarreau <w@....eu>
Subject: [ 01/48] x86_32, entry: Do syscall exit work on badsys
2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------
(CVE-2014-4508)
From: Andy Lutomirski <luto@...capital.net>
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.
This fixes an OOPS in the audit code when fast-path auditing is
enabled and sysenter gets a bad syscall nr (CVE-2014-4508).
This has probably been broken since Linux 2.6.27:
af0575bba0 i386 syscall audit fast-path
Cc: stable@...r.kernel.org
Cc: Roland McGrath <roland@...hat.com>
Reported-by: Toralf F�rster <toralf.foerster@....de>
Signed-off-by: Andy Lutomirski <luto@...capital.net>
Link: http://lkml.kernel.org/r/e09c499eade6fc321266dd6b54da7beb28d6991c.1403558229.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
(cherry picked from commit 554086d85e71f30abe46fc014fea31929a7c6a8a)
[WT: this fix is incorrect and requires the two following patches]
Signed-off-by: Willy Tarreau <w@....eu>
---
arch/x86/kernel/entry_32.S | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index c097e7d..40a0d02 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -445,9 +445,10 @@ sysenter_past_esp:
jnz sysenter_audit
sysenter_do_call:
cmpl $(nr_syscalls), %eax
- jae syscall_badsys
+ jae sysenter_badsys
call *sys_call_table(,%eax,4)
movl %eax,PT_EAX(%esp)
+sysenter_after_call:
LOCKDEP_SYS_EXIT
DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
@@ -702,7 +703,12 @@ END(syscall_fault)
syscall_badsys:
movl $-ENOSYS,PT_EAX(%esp)
- jmp resume_userspace
+ jmp syscall_exit
+END(syscall_badsys)
+
+sysenter_badsys:
+ movl $-ENOSYS,PT_EAX(%esp)
+ jmp sysenter_after_call
END(syscall_badsys)
CFI_ENDPROC
--
1.7.12.2.21.g234cd45.dirty
--
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