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authorAndreas Schwab <schwab@suse.de>2008-11-06 00:49:00 +0000
committerPaul Mackerras <paulus@samba.org>2008-11-11 19:42:22 +1100
commit77eb50aefa5dd2337246dce8b66e18e837c1a8bc (patch)
tree76232c81ab3f3badfbd45b5793dc4637fd2ed0dd
parentec5d7657f746c46b5fbb3dbec6d0f7d8b6b82961 (diff)
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: Andreas Schwab <schwab@suse.de> Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/kernel/signal_32.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index a6a43103655..b13abf30599 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -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]))
- return -EFAULT;
+ 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)