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Commit 77eb50ae authored by Andreas Schwab's avatar Andreas Schwab Committed by Paul Mackerras
Browse files

powerpc: Fix msr check in compat_sys_swapcontext 



The new context may not be 16-byte aligned, so the real address of the
mcontext structure should be read from the uc_regs pointer instead of
directly using the (unaligned) uc_mcontext field.

Signed-off-by: default avatarAndreas Schwab <schwab@suse.de>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent ec5d7657

arch/powerpc/kernel/signal_32.c

+15 −3
Original line number Diff line number Diff line
@@ -941,9 +941,21 @@ long sys_swapcontext(struct ucontext __user *old_ctx, 
#ifdef CONFIG_PPC64

	unsigned long new_msr = 0;



	if (new_ctx &&

	    get_user(new_msr, &new_ctx->uc_mcontext.mc_gregs[PT_MSR]))

	if (new_ctx) {

		struct mcontext __user *mcp;

		u32 cmcp;



		/*

		 * Get pointer to the real mcontext.  No need for

		 * access_ok since we are dealing with compat

		 * pointers.

		 */

		if (__get_user(cmcp, &new_ctx->uc_regs))

			return -EFAULT;

		mcp = (struct mcontext __user *)(u64)cmcp;

		if (__get_user(new_msr, &mcp->mc_gregs[PT_MSR]))

			return -EFAULT;

	}

	/*

	 * Check that the context is not smaller than the original

	 * size (with VMX but without VSX)