[PATCH] uml: use correct register file size everywhere

This patch uses MAX_REG_NR consistently to refer to the register file size.
 FRAME_SIZE isn't sufficient because on x86_64, it is smaller than the
ptrace register file size.  MAX_REG_NR was introduced as a consistent way
to get the number of registers, but wasn't used everywhere it should be.

When this causes a problem, it makes PTRACE_SETREGS fail on x86_64 because
of a corrupted segment register value in the known-good register file.  The
patch also adds a register dump at that point in case there are any future
problems here.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/um/os-Linux/sys-x86_64/registers.c b/arch/um/os-Linux/sys-x86_64/registers.c
index a2d7e0c603f7..e6fc2179d1bc 100644
--- a/arch/um/os-Linux/sys-x86_64/registers.c
+++ b/arch/um/os-Linux/sys-x86_64/registers.c
@@ -14,7 +14,7 @@
 
 /* These are set once at boot time and not changed thereafter */
 
-static unsigned long exec_regs[HOST_FRAME_SIZE];
+static unsigned long exec_regs[MAX_REG_NR];
 static unsigned long exec_fp_regs[HOST_FP_SIZE];
 
 void init_thread_registers(union uml_pt_regs *to)
@@ -72,7 +72,7 @@ void init_registers(int pid)
 
 void get_safe_registers(unsigned long *regs, unsigned long *fp_regs)
 {
-	memcpy(regs, exec_regs, HOST_FRAME_SIZE * sizeof(unsigned long));
+	memcpy(regs, exec_regs, sizeof(exec_regs));
 	if(fp_regs != NULL)
 		memcpy(fp_regs, exec_fp_regs,
 		       HOST_FP_SIZE * sizeof(unsigned long));