From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Tue, 5 May 2020 18:12:38 +0000 (+0100)
Subject: Fix sbrk in PIE binaries
X-Git-Tag: archive/raspbian/2.30-7+rpi1^2~80
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=d9c2fd74e4e5a9f243e468834d7fded76103b9a8;p=glibc.git

Fix sbrk in PIE binaries

In PIE mode, the program gets loaded at very low address, and thus _end is very
low, just before libraries, and thus initializing the brk to it does not make
sense, since there is no room left there. Hardcode the brk to 0x8000000 for now
as a workaround.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>


Gbp-Pq: Topic hurd-i386
Gbp-Pq: Name tg-pie-sbrk.diff
---

diff --git a/sysdeps/mach/hurd/brk.c b/sysdeps/mach/hurd/brk.c
index 54ef52fd3..a6444565d 100644
--- a/sysdeps/mach/hurd/brk.c
+++ b/sysdeps/mach/hurd/brk.c
@@ -143,8 +143,12 @@ init_brk (void)
   /* If _hurd_brk is already set, don't change it.  The assumption is that
      it was set in a previous run before something like Emacs's unexec was
      called and dumped all the data up to the break at that point.  */
-  if (_hurd_brk == 0)
+  if (_hurd_brk == 0) {
     _hurd_brk = (vm_address_t) &_end;
+    if (_hurd_brk < 0x8000000)
+      /* XXX: PIE case, get out of library area */
+      _hurd_brk = 0x8000000;
+  }
 
   pagend = round_page (_hurd_brk);