The patch titled
brk: COMPAT_BRK: fix detection of randomized brk
has been added to the -mm tree. Its filename is
brk-compat_brk-fix-detection-of-randomized-brk.patch
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------------------------------------------------------
Subject: brk: COMPAT_BRK: fix detection of randomized brk
From: Jiri Kosina <jkosina@xxxxxxx>
5520e89 ("brk: fix min_brk lower bound computation for COMPAT_BRK") tried
to get the whole logic of brk randomization for legacy (libc5-based)
applications finally right.
It turns out that the way to detect whether brk has actually been
randomized in the end or not introduced by that patch still doesn't work
for those binaries, as reported by Geert.
I don't like it, but currently see no better option than a bit flag in
task_struct to catch the CONFIG_COMPAT_BRK && randomize_va_space == 2
case.
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Tested-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_elf.c | 6 +++++-
include/linux/sched.h | 3 +++
mm/mmap.c | 2 +-
3 files changed, 9 insertions(+), 2 deletions(-)
diff -puN fs/binfmt_elf.c~brk-compat_brk-fix-detection-of-randomized-brk fs/binfmt_elf.c
--- a/fs/binfmt_elf.c~brk-compat_brk-fix-detection-of-randomized-brk
+++ a/fs/binfmt_elf.c
@@ -941,9 +941,13 @@ static int load_elf_binary(struct linux_
current->mm->start_stack = bprm->p;
#ifdef arch_randomize_brk
- if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1))
+ if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1)) {
current->mm->brk = current->mm->start_brk =
arch_randomize_brk(current->mm);
+#ifdef CONFIG_COMPAT_BRK
+ current->brk_randomized = 1;
+#endif
+ }
#endif
if (current->personality & MMAP_PAGE_ZERO) {
diff -puN include/linux/sched.h~brk-compat_brk-fix-detection-of-randomized-brk include/linux/sched.h
--- a/include/linux/sched.h~brk-compat_brk-fix-detection-of-randomized-brk
+++ a/include/linux/sched.h
@@ -1253,6 +1253,9 @@ struct task_struct {
#endif
struct mm_struct *mm, *active_mm;
+#ifdef CONFIG_COMPAT_BRK
+ unsigned brk_randomized:1;
+#endif
#if defined(SPLIT_RSS_COUNTING)
struct task_rss_stat rss_stat;
#endif
diff -puN mm/mmap.c~brk-compat_brk-fix-detection-of-randomized-brk mm/mmap.c
--- a/mm/mmap.c~brk-compat_brk-fix-detection-of-randomized-brk
+++ a/mm/mmap.c
@@ -263,7 +263,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
* randomize_va_space to 2, which will still cause mm->start_brk
* to be arbitrarily shifted
*/
- if (mm->start_brk > PAGE_ALIGN(mm->end_data))
+ if (current->brk_randomized)
min_brk = mm->start_brk;
else
min_brk = mm->end_data;
_
Patches currently in -mm which might be from jkosina@xxxxxxx are
origin.patch
linux-next.patch
brk-compat_brk-fix-detection-of-randomized-brk.patch
jbd-remove-dependency-on-__gfp_nofail.patch
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