Commit a5b4592cf77b973c29e7c9695873a26052b58951

Authored by Jiri Kosina
Committed by Linus Torvalds
1 parent 33dda515a1

brk: make sys_brk() honor COMPAT_BRK when computing lower bound

Fix a regression introduced by

commit 4cc6028d4040f95cdb590a87db478b42b8be0508
Author: Jiri Kosina <jkosina@suse.cz>
Date:   Wed Feb 6 22:39:44 2008 +0100

    brk: check the lower bound properly

The check in sys_brk() on minimum value the brk might have must take
CONFIG_COMPAT_BRK setting into account.  When this option is turned on
(i.e.  we support ancient legacy binaries, e.g.  libc5-linked stuff), the
lower bound on brk value is mm->end_code, otherwise the brk start is
allowed to be arbitrarily shifted.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 7 additions and 1 deletions Side-by-side Diff

... ... @@ -245,10 +245,16 @@
245 245 unsigned long rlim, retval;
246 246 unsigned long newbrk, oldbrk;
247 247 struct mm_struct *mm = current->mm;
  248 + unsigned long min_brk;
248 249  
249 250 down_write(&mm->mmap_sem);
250 251  
251   - if (brk < mm->start_brk)
  252 +#ifdef CONFIG_COMPAT_BRK
  253 + min_brk = mm->end_code;
  254 +#else
  255 + min_brk = mm->start_brk;
  256 +#endif
  257 + if (brk < min_brk)
252 258 goto out;
253 259  
254 260 /*