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Commit 55a423b6 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/kernel: fix ptrace peek/poke for floating point registers 



git commit 155e839a
"s390/kernel: dynamically allocate FP register save area"
introduced a regression in regard to ptrace.

If the vector register extension is not present or unused the
ptrace peek of a floating pointer register return incorrect data
and the ptrace poke to a floating pointer register overwrites the
task structure starting at task->thread.fpu.fprs.

Cc: stable@kernel.org # v4.3
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ef12cb90

arch/s390/kernel/ptrace.c

+4 −4
Original line number Diff line number Diff line
@@ -244,7 +244,7 @@ static unsigned long __peek_user(struct task_struct *child, addr_t addr) 
			       ((addr_t) child->thread.fpu.vxrs + 2*offset);

		else

			tmp = *(addr_t *)

			       ((addr_t) &child->thread.fpu.fprs + offset);

			       ((addr_t) child->thread.fpu.fprs + offset);



	} else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {

		/*
@@ -388,7 +388,7 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data) 
				child->thread.fpu.vxrs + 2*offset) = data;

		else

			*(addr_t *)((addr_t)

				&child->thread.fpu.fprs + offset) = data;

				child->thread.fpu.fprs + offset) = data;



	} else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {

		/*
@@ -622,7 +622,7 @@ static u32 __peek_user_compat(struct task_struct *child, addr_t addr) 
			       ((addr_t) child->thread.fpu.vxrs + 2*offset);

		else

			tmp = *(__u32 *)

			       ((addr_t) &child->thread.fpu.fprs + offset);

			       ((addr_t) child->thread.fpu.fprs + offset);



	} else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {

		/*
@@ -747,7 +747,7 @@ static int __poke_user_compat(struct task_struct *child, 
				child->thread.fpu.vxrs + 2*offset) = tmp;

		else

			*(__u32 *)((addr_t)

				&child->thread.fpu.fprs + offset) = tmp;

				child->thread.fpu.fprs + offset) = tmp;



	} else if (addr < (addr_t) (&dummy32->regs.per_info + 1)) {

		/*