Patch "h8300/ptrace: Fix incorrect register transfer count" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

h8300/ptrace: Fix incorrect register transfer count

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
h8300-ptrace-fix-incorrect-register-transfer-count.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dave Martin <[email protected]>
Date: Mon, 27 Mar 2017 15:10:54 +0100
Subject: h8300/ptrace: Fix incorrect register transfer count

From: Dave Martin <[email protected]>

commit 502585c7555083d4a949c08350306b9ec196779e upstream.

regs_set() and regs_get() are vulnerable to an off-by-1 buffer overrun if CONFIG_CPU_H8S is set, since this adds an extra entry to register_offset[] but not to user_regs_struct.

So, iterate over user_regs_struct based on its actual size, not based on the length of register_offset[].

---
 arch/h8300/kernel/ptrace.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

@@ -95,7 +95,8 @@ static int regs_get(struct task_struct *
 	long *reg = (long *)&regs;
 
 	/* build user regs in buffer */
-	for (r = 0; r < ARRAY_SIZE(register_offset); r++)
+	BUILD_BUG_ON(sizeof(regs) % sizeof(long) != 0);
+	for (r = 0; r < sizeof(regs) / sizeof(long); r++)
 		*reg++ = h8300_get_reg(target, r);
 
 	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,

@@ -113,7 +114,8 @@ static int regs_set(struct task_struct *
 	long *reg;
 
 	/* build user regs in buffer */
-	for (reg = (long *)&regs, r = 0; r < ARRAY_SIZE(register_offset); r++)
+	BUILD_BUG_ON(sizeof(regs) % sizeof(long) != 0);
+	for (reg = (long *)&regs, r = 0; r < sizeof(regs) / sizeof(long); r++)
 		*reg++ = h8300_get_reg(target, r);
 
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,

@@ -122,7 +124,7 @@ static int regs_set(struct task_struct *
 		return ret;
 
 	/* write back to pt_regs */
-	for (reg = (long *)&regs, r = 0; r < ARRAY_SIZE(register_offset); r++)
+	for (reg = (long *)&regs, r = 0; r < sizeof(regs) / sizeof(long); r++)
 		h8300_put_reg(target, r, *reg++);
 	return 0;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/metag-ptrace-reject-partial-nt_metag_rpipe-writes.patch queue-4.4/metag-ptrace-preserve-previous-registers-for-short-regset-write.patch queue-4.4/metag-ptrace-provide-default-txstatus-for-short-nt_prstatus.patch queue-4.4/c6x-ptrace-remove-useless-ptrace_setregset-implementation.patch queue-4.4/mips-ptrace-preserve-previous-registers-for-short-regset-write.patch queue-4.4/h8300-ptrace-fix-incorrect-register-transfer-count.patch queue-4.4/sparc-ptrace-preserve-previous-registers-for-short-regset-write.patch