metag/ptrace: Provide default TXSTATUS for short NT_PRSTATUS

Ensure that if userspace supplies insufficient data to PTRACE_SETREGSET
to fill TXSTATUS, a well-defined default value is used, based on the
task's current value.

Suggested-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/metag/kernel/ptrace.c b/arch/metag/kernel/ptrace.c
index ae659ba619487d67be09a8cd792f957be1709fae..2e4dfc15abd330ac9a38cd2df6d1779cc6bd0d9b 100644 (file)
--- a/arch/metag/kernel/ptrace.c
+++ b/arch/metag/kernel/ptrace.c
@@ -24,6 +24,16 @@
  * user_regset definitions.
  */
 
+static unsigned long user_txstatus(const struct pt_regs *regs)
+{
+       unsigned long data = (unsigned long)regs->ctx.Flags;
+
+       if (regs->ctx.SaveMask & TBICTX_CBUF_BIT)
+               data |= USER_GP_REGS_STATUS_CATCH_BIT;
+
+       return data;
+}
+
 int metag_gp_regs_copyout(const struct pt_regs *regs,
                          unsigned int pos, unsigned int count,
                          void *kbuf, void __user *ubuf)
@@ -62,9 +72,7 @@ int metag_gp_regs_copyout(const struct pt_regs *regs,
        if (ret)
                goto out;
        /* TXSTATUS */
-       data = (unsigned long)regs->ctx.Flags;
-       if (regs->ctx.SaveMask & TBICTX_CBUF_BIT)
-               data |= USER_GP_REGS_STATUS_CATCH_BIT;
+       data = user_txstatus(regs);
        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                                  &data, 4*25, 4*26);
        if (ret)
@@ -119,6 +127,7 @@ int metag_gp_regs_copyin(struct pt_regs *regs,
        if (ret)
                goto out;
        /* TXSTATUS */
+       data = user_txstatus(regs);
        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                 &data, 4*25, 4*26);
        if (ret)