[PATCH 3.2 66/94] s390/ptrace: fix PSW mask check
From: Ben Hutchings <hidden>
Date: 2014-08-04 17:10:52
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3.2.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Martin Schwidefsky <redacted> 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 <redacted> Signed-off-by: Ben Hutchings <redacted> ---
--- 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) |