On Mon, 2014-07-28 at 21:45 -0700, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > 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. [...] This backport is wrong. I think Martin's version for 3.2 (attached) should also work for 3.4 and 3.10. Ben. -- Ben Hutchings Larkinson's Law: All laws are basically false.
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Mon, 23 Jun 2014 14:43:06 +0200
Subject: s390/ptrace: fix PSW mask check
commit dab6cf55f81a6e16b8147aed9a843e1691dcd318 upstream.
The PSW mask check of the PTRACE_POKEUSR_AREA command is incorrect.
For the default user_mode=home address space layout the psw_user_bits
variable has the home space address-space-control bits set. But the
PSW_MASK_USER contains PSW_MASK_ASC, the ptrace validity check for the
PSW mask will therefore always fail.
Fixes CVE-2014-3534
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -292,7 +292,9 @@ 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_user_bits) & ~PSW_MASK_USER) ||
+ (((data^psw_user_bits) & PSW_MASK_ASC) &&
+ ((data|psw_user_bits) & PSW_MASK_ASC) == PSW_MASK_ASC) ||
((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))))
/* Invalid psw mask. */
return -EINVAL;
@@ -595,7 +597,10 @@ 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) ||
+ (((tmp^psw32_user_bits) & PSW32_MASK_ASC) &&
+ ((tmp|psw32_user_bits) & PSW32_MASK_ASC)
+ == PSW32_MASK_ASC))
/* Invalid psw mask. */
return -EINVAL;
regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
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