mips/ptrace: Preserve previous registers for short regset write
commit d614fd58a2834cfe4efa472c33c8f3ce2338b09b upstream.
Ensure that if userspace supplies insufficient data to PTRACE_SETREGSET
to fill all the registers, the thread's old registers are preserved.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index a92994d..bf83dc1 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -485,7 +485,8 @@
&target->thread.fpu,
0, sizeof(elf_fpregset_t));
- for (i = 0; i < NUM_FPU_REGS; i++) {
+ BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
+ for (i = 0; i < NUM_FPU_REGS && count >= sizeof(elf_fpreg_t); i++) {
err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&fpr_val, i * sizeof(elf_fpreg_t),
(i + 1) * sizeof(elf_fpreg_t));