[glibc] Fix __minimal_malloc segfaults in __mmap due to stack-protector

[glibc] Fix __minimal_malloc segfaults in __mmap due to stack-protector

[Stefan Liebler]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ff3cb03f38f851bbb066206573dc68914920be0a

commit ff3cb03f38f851bbb066206573dc68914920be0a
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Thu Dec 16 12:47:11 2021 +0100

    Fix __minimal_malloc segfaults in __mmap due to stack-protector
    
    Starting with commit b05fae4d8e34604a72ee36d2d3164391b76fcf0b
    "elf: Use the minimal malloc on tunables_strdup",
    I get lots of segfaults in static tests on s390x when also using, e.g.:
    export GLIBC_TUNABLES="glibc.elision.enable=1"
    
    tunables_strdup callls __minimal_malloc which tries to call __mmap
    due to insufficient space left. __mmap itself first setups a new
    stack frame and segfaults when copying the stack-protector canary
    from thread-pointer. The latter one is not yet setup.
    
    Thus this patch also turns off stack-protection for mmap.
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

Diff:
---
 misc/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/misc/Makefile b/misc/Makefile
index 3b66cb9f6a..db40312ba9 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -149,6 +149,10 @@ CFLAGS-sbrk.o = $(no-stack-protector)
 CFLAGS-sbrk.op = $(no-stack-protector)
 CFLAGS-brk.o = $(no-stack-protector)
 CFLAGS-brk.op = $(no-stack-protector)
+CFLAGS-mmap.o = $(no-stack-protector)
+CFLAGS-mmap.op = $(no-stack-protector)
+CFLAGS-mmap64.o = $(no-stack-protector)
+CFLAGS-mmap64.op = $(no-stack-protector)
 
 include ../Rules