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Commit 77eb50aefa5dd2337246dce8b66e18e837c1a8bc

Authored by Andreas Schwab
Committed by Paul Mackerras
1 parent ec5d7657f7
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

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>

Showing 1 changed file with 15 additions and 3 deletions Side-by-side Diff

arch/powerpc/kernel/signal_32.c
Diff comments   View file @ 77eb50a
... ... @@ -941,9 +941,21 @@
941 941 #ifdef CONFIG_PPC64
942 942 unsigned long new_msr = 0;
943 943  
944   - if (new_ctx &&
945   - get_user(new_msr, &new_ctx->uc_mcontext.mc_gregs[PT_MSR]))
946   - return -EFAULT;
  944 + if (new_ctx) {
  945 + struct mcontext __user *mcp;
  946 + u32 cmcp;
  947 +
  948 + /*
  949 + * Get pointer to the real mcontext. No need for
  950 + * access_ok since we are dealing with compat
  951 + * pointers.
  952 + */
  953 + if (__get_user(cmcp, &new_ctx->uc_regs))
  954 + return -EFAULT;
  955 + mcp = (struct mcontext __user *)(u64)cmcp;
  956 + if (__get_user(new_msr, &mcp->mc_gregs[PT_MSR]))
  957 + return -EFAULT;
  958 + }
947 959 /*
948 960 * Check that the context is not smaller than the original
949 961 * size (with VMX but without VSX)