|author||Samuel Thibault <firstname.lastname@example.org>||2020-08-06 00:01:18 +0200|
|committer||Samuel Thibault <email@example.com>||2020-08-06 00:01:18 +0200|
Use commit messaget/pie-sbrk
1 files changed, 24 insertions, 16 deletions
@@ -1,21 +1,29 @@
-Subject: Fix sbrk in PIE binaries
+Committed from glibc 2.33
-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.
+From: Samuel Thibault <firstname.lastname@example.org>
+hurd: Rework sbrk
+Making the brk start exactly at the end of the main application binary was
+requiring to get it through the _end symbol, which does not work any more
+with recent toolchains, and actually produces in libc.so a confusing
+external _end symbol that produces odd results, see
-YYYY-MM-DD Samuel Thibault <email@example.com>
- Thomas Schwinge <firstname.lastname@example.org>
+Trying to do so is quite outdated anyway with the tendency for address
+Using _end was also allowing to include the main binary data within
+the RLIMIT_DATA, but this also seems outdated with dynamic library
+loading, and nowadays' memory consumption via malloc and mmap rather than
+This adds a BRK_START macro in <vm_param.h> that just tells where we
+want to start the brk, and thus removes the _end symbol.
+* sysdeps/mach/hurd/i386/vm_param.h: New file.
+* sysdeps/mach/hurd/brk.c: Use BRK_START as brk start instead of _end.
+Also ignore __data_start.
+* hurd/Versions: Remove _end symbol.
+* sysdeps/mach/hurd/i386/libc.abilist: Remove _end symbol.
- * sysdeps/mach/hurd/brk.c (init_brk): Fix for PIE executables.
- * misc/tst-sbrk.c: New file.
- * misc/tst-sbrk-pie.c: Likewise.
- * misc/tst-sbrk-static.c: Likewise.
- * misc/Makefile (tests): Add tst-sbrk, tst-sbrk-pie, tst-sbrk-static.
- (tests-pie): Add tst-sbrk-pie.
- (tests-static): Add tst-sbrk-static.