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Commit dab6cf55 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 8fb878c5

arch/s390/kernel/ptrace.c

+10 −2
Original line number Diff line number Diff line
@@ -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;