Re: [PATCH v2] binfmt_elf: Fix PIE execution with randomizationdisabled (was Re: [RFC PATCH] binfmt_elf: Fix PIE execution with randomizationdisabled)
From: Jiri Kosina
Date: Sat Oct 08 2011 - 18:35:41 EST
On Mon, 3 Oct 2011, Andrew Morton wrote:
> > Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
> > ---
> > fs/binfmt_elf.c | 5 ++++-
> > 1 files changed, 4 insertions(+), 1 deletions(-)
> >
> > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> > index dd0fdfc..bb11fe4 100644
> > --- a/fs/binfmt_elf.c
> > +++ b/fs/binfmt_elf.c
> > @@ -795,7 +795,10 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
> > * might try to exec. This is because the brk will
> > * follow the loader, and is not movable. */
> > #if defined(CONFIG_X86) || defined(CONFIG_ARM)
> > - load_bias = 0;
> > + if (current->flags & PF_RANDOMIZE)
> > + load_bias = 0;
> > + else
> > + load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
> > #else
> > load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
> > #endif
>
> Guys, it took several people several days and 10+ emails to work out
> what's happening in there, and the first attempt to fix it was buggy.
> This is all a huuuuge signal that the code is unobvious, hard to
> understand, hard to maintain.
>
> Please, let's get a good code comment in there while it's fresh in your
> minds. So the next person who comes along doesn't have the same amount
> of difficulty?
BTW, after thinking about this a little bit more, maybe the patch below
would be worthwile and could save some mis-routed e-mails and bugreports
in the future ...
From: Jiri Kosina <jkosina@xxxxxxx>
Subject: [PATCH] MAINTAINERS: add ASLR maintainer
Since achieving the full ASLR by merging the PIE randomization in commit
cc503c1b43 ("x86: PIE executable randomization"), I have been dealing with
most (if not all) of the bugreports reported against userspace address
space randomization, so it might be a good idea to provide a decent
contact point in MAINTAINERS.
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
MAINTAINERS | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index ace8f9c..c362845 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -317,6 +317,10 @@ W: http://wiki.analog.com/AD7879
S: Supported
F: drivers/input/touchscreen/ad7879.c
+ADDRESS SPACE LAYOUT RANDOMIZATION (ASLR)
+M: Jiri Kosina <jkosina@xxxxxxx>
+S: Maintained
+
ADM1025 HARDWARE MONITOR DRIVER
M: Jean Delvare <khali@xxxxxxxxxxxx>
L: lm-sensors@xxxxxxxxxxxxxx
--
1.7.3.1
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