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s390/ptrace: fix PSW mask check

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commit dab6cf55f8 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@de.ibm.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martin Schwidefsky
2014-06-23 15:29:40 +02:00
committed by Greg Kroah-Hartman
parent e1d8240bdd
commit a940d7b23b
1 changed files with 7 additions and 2 deletions
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9
arch/s390/kernel/ptrace.c
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@@ -314,7 +314,9 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
* 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;
@@ -627,7 +629,10 @@ static int __poke_user_compat(struct task_struct *child,
*/
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) |