[glibc/arm/morello/main] cheri: fix invalid pointer use after realloc in localealias

[Szabolcs Nagy <nsz@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=cf06645316e11077afbc9731693fd19e55619f59

commit cf06645316e11077afbc9731693fd19e55619f59
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Fri Mar 18 06:55:31 2022 +0000

    cheri: fix invalid pointer use after realloc in localealias
    
    This code updates pointers to a reallocated buffer to point to the new
    buffer.  It is not conforming (does arithmetics with freed pointers),
    but it also creates invalid capabilities because the provenance is
    derived from the original freed pointers instead of the new buffer.
    
    Change the arithmetics so provenance is derived from the new buffer.
    The conformance issue is not fixed.

Diff:
---
 intl/localealias.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/intl/localealias.c b/intl/localealias.c
index b36092363a..0401f35f9d 100644
--- a/intl/localealias.c
+++ b/intl/localealias.c
@@ -340,8 +340,10 @@ read_alias_file (const char *fname, int fname_len)
 
 			  for (i = 0; i < nmap; i++)
 			    {
-			      map[i].alias += new_pool - string_space;
-			      map[i].value += new_pool - string_space;
+			      map[i].alias = new_pool
+					     + (map[i].alias - string_space);
+			      map[i].value = new_pool
+					     + (map[i].value - string_space);
 			    }
 			}