[glibc] _hurd_intr_rpc_mach_msg: handle message iteration correctly.

[Samuel Thibault <sthibaul@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f11a92993c45a91c3237733486ce2b8735af2ba0

commit f11a92993c45a91c3237733486ce2b8735af2ba0
Author: Flavio Cruz <flaviocruz@gmail.com>
Date:   Sat Nov 18 18:18:44 2023 -0500

    _hurd_intr_rpc_mach_msg: handle message iteration correctly.
    
    The `ty` pointer is only set at the end of the loop so that
    `msgtl_header.msgt_inline` and `msgtl_header.msgt_deallocate` remain
    valid. Also, when deallocating memory, we use the length from the
    message directly rather than hard coding mach_port_t since we want to
    deallocate any kind of OOL data.
    Message-ID: <ZVlGVD6eEN-dXsOr@jupiter.tail36e24.ts.net>

Diff:
---
 hurd/intr-msg.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/hurd/intr-msg.c b/hurd/intr-msg.c
index 98f588f206..737bfe0ffb 100644
--- a/hurd/intr-msg.c
+++ b/hurd/intr-msg.c
@@ -186,12 +186,14 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
 	      mach_msg_type_size_t size;
 	      mach_msg_type_number_t number;
 
-	      inline void clean_ports (mach_port_t *ports, int dealloc)
+	      inline void clean_ports_and_memory (char *data, const vm_size_t length,
+						int dealloc)
 		{
 		  mach_msg_type_number_t i;
 		  switch (name)
 		    {
 		    case MACH_MSG_TYPE_MOVE_SEND:
+		      mach_port_t *ports = (mach_port_t *) data;
 		      for (i = 0; i < number; i++)
 			__mach_port_deallocate (__mach_task_self (), *ports++);
 		      if (ty->msgtl_header.msgt_longform)
@@ -207,40 +209,38 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
 			assert (! "unexpected port type in interruptible RPC");
 		    }
 		  if (dealloc)
-		    __vm_deallocate (__mach_task_self (),
-				     (vm_address_t) ports,
-				     number * sizeof (mach_port_t));
+		    __vm_deallocate (__mach_task_self (), (vm_address_t) data, length);
 		}
 
+	      char *data;
 	      if (ty->msgtl_header.msgt_longform)
 		{
 		  name = ty->msgtl_name;
 		  size = ty->msgtl_size;
 		  number = ty->msgtl_number;
-		  ty = (void *) ty + sizeof (mach_msg_type_long_t);
+		  data = (char *) ty + sizeof (mach_msg_type_long_t);
 		}
 	      else
 		{
 		  name = ty->msgtl_header.msgt_name;
 		  size = ty->msgtl_header.msgt_size;
 		  number = ty->msgtl_header.msgt_number;
-		  ty = (void *) ty + sizeof (mach_msg_type_t);
+		  data = (char *) ty + sizeof (mach_msg_type_t);
 		}
 
+	      const vm_size_t length = ((number * size) + 7) >> 3;
 	      if (ty->msgtl_header.msgt_inline)
 		{
 		  /* Calculate length of data in bytes.  */
-		  const vm_size_t length = ((number * size) + 7) >> 3;
-		  clean_ports ((void *) ty, 0);
+		  clean_ports_and_memory (data, length, 0);
 		  /* Move to the next argument.  */
-		  ty = (void *) PTR_ALIGN_UP ((char *) ty + length,
-		      __alignof__ (uintptr_t));
+		  ty = (void *) PTR_ALIGN_UP (data + length, __alignof__ (uintptr_t));
 		}
 	      else
 		{
-		  clean_ports (*(void **) ty,
+		  clean_ports_and_memory (*(void **) data, length,
 			       ty->msgtl_header.msgt_deallocate);
-		  ty = (void *) ty + sizeof (void *);
+		  ty = (void *) data + sizeof (void *);
 		}
 	    }
 #else  /* Untyped Mach IPC flavor. */