This is a note to let you know that I've just added the patch titled
s390/ptrace: fix PSW mask check
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-ptrace-fix-psw-mask-check.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dab6cf55f81a6e16b8147aed9a843e1691dcd318 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Mon, 23 Jun 2014 15:29:40 +0200
Subject: s390/ptrace: fix PSW mask check
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
commit dab6cf55f81a6e16b8147aed9a843e1691dcd318 upstream.
The PSW mask check of the PTRACE_POKEUSR_AREA command is incorrect.
The PSW_MASK_USER define contains the PSW_MASK_ASC bits, the ptrace
interface accepts all combinations for the address-space-control
bits. To protect the kernel space the PSW mask check in ptrace needs
to reject the address-space-control bit combination for home space.
Fixes CVE-2014-3534
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
[bwh: Backported to 3.2:
- The PSW user-settable bitmasks are constant, never including PSW_MASK_RI
- The kernel can run in either home or primary space, so instead of
checking that the ASC bits are not equal to PSW_ASC_HOME, we have to
check that they don't match psw_kernel_bits
- For the same reason, the required values of non-user-settable bits
are variables (psw_user_bits/psw32_user_bits) and remain so]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/ptrace.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -291,11 +291,18 @@ static int __poke_user(struct task_struc
/*
* psw and gprs are stored on the stack
*/
- if (addr == (addr_t) &dummy->regs.psw.mask &&
- ((data & ~PSW_MASK_USER) != psw_user_bits ||
- ((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))))
- /* Invalid psw mask. */
- return -EINVAL;
+ if (addr == (addr_t) &dummy->regs.psw.mask) {
+ if ((data ^ psw_user_bits) & ~PSW_MASK_USER)
+ /* Invalid psw mask. */
+ return -EINVAL;
+ if ((data & PSW_MASK_ASC) ==
+ (psw_kernel_bits & PSW_MASK_ASC))
+ /* Invalid address-space-control bits */
+ return -EINVAL;
+ if ((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))
+ /* Invalid addressing mode bits */
+ return -EINVAL;
+ }
*(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr) = data;
} else if (addr < (addr_t) (&dummy->regs.orig_gpr2)) {
@@ -595,9 +602,13 @@ static int __poke_user_compat(struct tas
*/
if (addr == (addr_t) &dummy32->regs.psw.mask) {
/* Build a 64 bit psw mask from 31 bit mask. */
- if ((tmp & ~PSW32_MASK_USER) != psw32_user_bits)
+ if ((tmp ^ psw32_user_bits) & ~PSW32_MASK_USER)
/* Invalid psw mask. */
return -EINVAL;
+ if ((data & PSW32_MASK_ASC) ==
+ ((psw_kernel_bits & PSW_MASK_ASC) >> 32))
+ /* Invalid address-space-control bits */
+ return -EINVAL;
regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
(regs->psw.mask & PSW_MASK_BA) |
(__u64)(tmp & PSW32_MASK_USER) << 32;
Patches currently in stable-queue which might be from schwidefsky@xxxxxxxxxx are
queue-3.4/s390-ptrace-fix-psw-mask-check.patch
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