[4.9,074/130] arm64/ptrace: Reject attempts to set incomplete hardware breakpoint fields
diff mbox series

Message ID 20170124075537.971052688@linuxfoundation.org
State New, archived
Headers show
Series
  • 4.9.6-stable review
Related show

Commit Message

Greg KH Jan. 24, 2017, 7:55 a.m. UTC
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dave Martin <Dave.Martin@arm.com>

commit ad9e202aa1ce571b1d7fed969d06f66067f8a086 upstream.

We cannot preserve partial fields for hardware breakpoints, because
the values written by userspace to the hardware breakpoint
registers can't subsequently be recovered intact from the hardware.

So, just reject attempts to write incomplete fields with -EINVAL.

Fixes: 478fcb2cdb23 ("arm64: Debugging support")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <Will.Deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/ptrace.c |    4 ++++
 1 file changed, 4 insertions(+)

Patch
diff mbox series

--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -550,6 +550,8 @@  static int hw_break_set(struct task_stru
 	/* (address, ctrl) registers */
 	limit = regset->n * regset->size;
 	while (count && offset < limit) {
+		if (count < PTRACE_HBP_ADDR_SZ)
+			return -EINVAL;
 		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &addr,
 					 offset, offset + PTRACE_HBP_ADDR_SZ);
 		if (ret)
@@ -559,6 +561,8 @@  static int hw_break_set(struct task_stru
 			return ret;
 		offset += PTRACE_HBP_ADDR_SZ;
 
+		if (!count)
+			break;
 		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ctrl,
 					 offset, offset + PTRACE_HBP_CTRL_SZ);
 		if (ret)