powerpc: Fix machine check problem on 32-bit kernels
This fixes a bug found by Dave Jones that means that it is possible
for userspace to provoke a machine check on 32-bit kernels. This
also fixes a couple of other places where I found similar problems
by inspection.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 01e3c08..8fdeca2 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -803,10 +803,13 @@
if (__get_user(cmcp, &ucp->uc_regs))
return -EFAULT;
mcp = (struct mcontext __user *)(u64)cmcp;
+ /* no need to check access_ok(mcp), since mcp < 4GB */
}
#else
if (__get_user(mcp, &ucp->uc_regs))
return -EFAULT;
+ if (!access_ok(VERIFY_READ, mcp, sizeof(*mcp)))
+ return -EFAULT;
#endif
restore_sigmask(&set);
if (restore_user_regs(regs, mcp, sig))
@@ -908,13 +911,14 @@
{
struct sig_dbg_op op;
int i;
+ unsigned char tmp;
unsigned long new_msr = regs->msr;
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
unsigned long new_dbcr0 = current->thread.dbcr0;
#endif
for (i=0; i<ndbg; i++) {
- if (__copy_from_user(&op, dbg, sizeof(op)))
+ if (copy_from_user(&op, dbg + i, sizeof(op)))
return -EFAULT;
switch (op.dbg_type) {
case SIG_DBG_SINGLE_STEPPING:
@@ -959,6 +963,11 @@
current->thread.dbcr0 = new_dbcr0;
#endif
+ if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
+ || __get_user(tmp, (u8 __user *) ctx)
+ || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
+ return -EFAULT;
+
/*
* If we get a fault copying the context into the kernel's
* image of the user's registers, we can't just return -EFAULT
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 27f65b9..c2db642 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -182,6 +182,8 @@
err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
if (err)
return err;
+ if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
+ return -EFAULT;
/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
if (v_regs != 0 && (msr & MSR_VEC) != 0)
err |= __copy_from_user(current->thread.vr, v_regs,