PR/55043 CVS commit: src/libexec/ld.elf_so

["Jason R Thorpe" <thorpej%netbsd.org@localhost>]

The following reply was made to PR toolchain/55043; it has been noted by GNATS.

From: "Jason R Thorpe" <thorpej%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/55043 CVS commit: src/libexec/ld.elf_so
Date: Wed, 4 Mar 2020 01:21:17 +0000

 Module Name:	src
 Committed By:	thorpej
 Date:		Wed Mar  4 01:21:17 UTC 2020
 
 Modified Files:
 	src/libexec/ld.elf_so: headers.c map_object.c rtld.c
 
 Log Message:
 PT_GNU_RELRO segments are arranged such that their vaddr + memsz ends
 on a linker common page size boundary.  However, if the common page size
 used by the linker is less than the VM page size being used by the kernel,
 this can end up in the middle of a VM page and when the region is write-
 protected, this can cause objects in neighboring .data to get incorrectly
 write-protected, resulting in a crash.
 
 Avoid this situation by calculating the end of the RELRO region not by
 rounding memsz up to the VM page size, but rather by adding vaddr + memsz
 and then truncating to the VM page size.
 
 Fixes PR toolchain/55043.
 
 XXX pullup-9
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.67 -r1.68 src/libexec/ld.elf_so/headers.c
 cvs rdiff -u -r1.60 -r1.61 src/libexec/ld.elf_so/map_object.c
 cvs rdiff -u -r1.202 -r1.203 src/libexec/ld.elf_so/rtld.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.