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s390/ptrace: fix PSW mask check 

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

Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2014-06-23 15:29:40 +02:00
parent 8fb878c5f1
commit dab6cf55f8
1 changed files with 10 additions and 2 deletions
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12
arch/s390/kernel/ptrace.c
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@ -334,9 +334,14 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
unsigned long mask = PSW_MASK_USER;
mask |= is_ri_task(child) ? PSW_MASK_RI : 0;
if ((data & ~mask) != PSW_USER_BITS)
if ((data ^ PSW_USER_BITS) & ~mask)
/* Invalid psw mask. */
return -EINVAL;
if ((data & PSW_MASK_ASC) == PSW_ASC_HOME)
/* 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;
@ -672,9 +677,12 @@ static int __poke_user_compat(struct task_struct *child,
mask |= is_ri_task(child) ? PSW32_MASK_RI : 0;
/* Build a 64 bit psw mask from 31 bit mask. */
if ((tmp & ~mask) != PSW32_USER_BITS)
if ((tmp ^ PSW32_USER_BITS) & ~mask)
/* Invalid psw mask. */
return -EINVAL;
if ((data & PSW32_MASK_ASC) == PSW32_ASC_HOME)
/* Invalid address-space-control bits */
return -EINVAL;
regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
(regs->psw.mask & PSW_MASK_BA) |
(__u64)(tmp & mask) << 32;