[tip:x86/urgent] x86_32, entry: Do syscall exit work on badsys ( CVE-2014-4508)
From: tip-bot for Andy Lutomirski
Date: Mon Jun 23 2014 - 18:19:19 EST
Commit-ID: 554086d85e71f30abe46fc014fea31929a7c6a8a
Gitweb: http://git.kernel.org/tip/554086d85e71f30abe46fc014fea31929a7c6a8a
Author: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
AuthorDate: Mon, 23 Jun 2014 14:22:15 -0700
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Mon, 23 Jun 2014 14:59:26 -0700
x86_32, entry: Do syscall exit work on badsys (CVE-2014-4508)
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@xxxxxxxxxxxxxxx
Cc: Roland McGrath <roland@xxxxxxxxxx>
Reported-by: Toralf FÃrster <toralf.foerster@xxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/e09c499eade6fc321266dd6b54da7beb28d6991c.1403558229.git.luto@xxxxxxxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
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 f0da82b..dbaa23e 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -423,9 +423,10 @@ 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
@@ -675,7 +676,12 @@ 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
--
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