[x86] x86_32, entry: Do syscall exit work on badsys (CVE-2014-4508)

svn path=/dists/sid/linux/; revision=21477

debian/changelog

@@ -53,6 +53,7 @@ linux (3.14.9-1) UNRELEASED; urgency=medium
     - bugfix, handling an error in opening a FIFO
     - propagate aufs file references to new vmas created by remap_file_pages()
   * linux-image: Make initramfs support unconditional
+  * [x86] x86_32, entry: Do syscall exit work on badsys (CVE-2014-4508)
 
   [ Aurelien Jarno ]
   * [arm64] Enable COMPAT to support 32-bit binaries.

debian/patches/bugfix/x86/x86_32-entry-Do-syscall-exit-work-on-badsys-CVE-2014.patch

@@ -0,0 +1,56 @@
+From: Andy Lutomirski <luto@amacapital.net>
+Date: Mon, 23 Jun 2014 14:22:15 -0700
+Subject: x86_32, entry: Do syscall exit work on badsys (CVE-2014-4508)
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+Origin: https://git.kernel.org/linus/554086d85e71f30abe46fc014fea31929a7c6a8a
+
+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@vger.kernel.org
+Cc: Roland McGrath <roland@redhat.com>
+Reported-by: Toralf Förster <toralf.foerster@gmx.de>
+Signed-off-by: Andy Lutomirski <luto@amacapital.net>
+Link: http://lkml.kernel.org/r/e09c499eade6fc321266dd6b54da7beb28d6991c.1403558229.git.luto@amacapital.net
+Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
+---
+ arch/x86/kernel/entry_32.S | 10 ++++++++--
+ 1 file changed, 8 insertions(+), 2 deletions(-)
+
+--- a/arch/x86/kernel/entry_32.S
++++ b/arch/x86/kernel/entry_32.S
+@@ -431,9 +431,10 @@ 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
+@@ -688,7 +689,12 @@ 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
+ /*

debian/patches/series

@@ -92,3 +92,4 @@ debian/dma-avoid-abi-change-in-3.14.6.patch
 debian/vfs-avoid-abi-change-for-cve-2014-4014.patch
 bugfix/all/SCSI-Fix-spurious-request-sense-in-error-handling.patch
 debian/alsa-avoid-abi-change-for-cve-2014-4652-fix.patch
+bugfix/x86/x86_32-entry-Do-syscall-exit-work-on-badsys-CVE-2014.patch