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SubjectRe: m68k libc5 regression
On Mon, 26 May 2008, Geert Uytterhoeven wrote:

> Recently I noticed a regression when running an old libc5 binary
> (amiga-lilo) on m68k. It fails with the error message:

Hmm, libc5 is known to make broken assumptions about brk location, that's
why we introduced CONFIG_COMPAT_BRK, do you have that option turned on?

> So I bisected it to:
> commit 4cc6028d4040f95cdb590a87db478b42b8be0508
> Author: Jiri Kosina <jkosina@suse.cz>
> Date: Wed Feb 6 22:39:44 2008 +0100
> brk: check the lower bound properly

Indeed, this should take CONFIG_COMPAT_BRK into account. Does the patch
below fix it? (assuming that you have CONFIG_COMPAT_BRK=y):



From: Jiri Kosina <jkosina@suse.cz>

brk: check 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>

diff --git a/mm/mmap.c b/mm/mmap.c
index fac6633..834118b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -245,10 +245,16 @@ asmlinkage unsigned long sys_brk(unsigned long brk)
unsigned long rlim, retval;
unsigned long newbrk, oldbrk;
struct mm_struct *mm = current->mm;
+ unsigned long min_brk;

down_write(&mm->mmap_sem);

- if (brk < mm->start_brk)
+#ifdef CONFIG_COMPAT_BRK
+ min_brk = mm->end_code;
+#else
+ min_brk = mm->start_brk;
+#endif
+ if (brk < min_brk)
goto out;

/*

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