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From: Jeff King <peff@peff.net>
To: Jann Horn <jannh@google.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	pclouds@gmail.com, johannes.schindelin@gmx.de, nico@cam.org
Subject: Re: [PATCH 2/3] t/helper/test-delta: segfault on OOB access
Date: Wed, 29 Aug 2018 17:48:36 -0400	[thread overview]
Message-ID: <20180829214836.GE29880@sigill.intra.peff.net> (raw)
In-Reply-To: <20180829214621.GD29880@sigill.intra.peff.net>

On Wed, Aug 29, 2018 at 05:46:21PM -0400, Jeff King wrote:

> > I think even with ASAN, you'd still need read_in_full() or an mmap()
> > wrapper that fiddles with the ASAN shadow, because mmap() always maps
> > whole pages:
> > 
> > $ cat mmap-read-asan-blah.c
> > #include <sys/mman.h>
> > #include <stdlib.h>
> > int main(void) {
> >   volatile char *p = mmap(NULL, 1, PROT_READ|PROT_WRITE,
> > MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
> >   p[200] = 1;
> > }
> > $ gcc -o mmap-read-asan-blah mmap-read-asan-blah.c -fsanitize=address
> > $ ./mmap-read-asan-blah
> > $
> 
> Yeah, I was just trying to run your tests with ASan and couldn't
> convince it to complain. I also tried MSan, but no luck.
> 
> > But that aside, you do have a point about having some custom hack for
> > a single patch.
> 
> I'm also not sure how portable it is. Looks like we have a Windows
> wrapper for getpagesize(), but I don't see any other uses of mprotect().

Actually, there is no real need for this test helper to use mmap. I
suppose we could swap it out for malloc + read_in_full() and let ASan
(or even valgrind) handle the tricky parts.

-Peff

  reply	other threads:[~2018-08-29 21:48 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-29 20:58 [PATCH 1/3] patch-delta: fix oob read Jann Horn
2018-08-29 20:58 ` [PATCH 2/3] t/helper/test-delta: segfault on OOB access Jann Horn
2018-08-29 21:34   ` Jeff King
2018-08-29 21:40     ` Jann Horn
2018-08-29 21:46       ` Jeff King
2018-08-29 21:48         ` Jeff King [this message]
2018-08-29 20:58 ` [PATCH 3/3] t5303: add tests for corrupted deltas Jann Horn
2018-08-29 22:03   ` Jeff King
2018-08-29 22:30     ` Jeff King
2018-08-29 21:20 ` [PATCH 1/3] patch-delta: fix oob read Jeff King
2018-08-29 22:18   ` Jeff King
2018-08-30  7:05 ` [PATCH 0/5] handle corruption in patch-delta Jeff King
2018-08-30  7:07   ` [PATCH 1/5] test-delta: read input into a heap buffer Jeff King
2018-08-30  7:09   ` [PATCH 2/5] t5303: test some corrupt deltas Jeff King
2018-08-30 17:38     ` Junio C Hamano
2018-08-30 18:42       ` Jeff King
2018-08-30 18:44         ` Jeff King
2018-08-30 18:50           ` Junio C Hamano
2018-08-30 19:13             ` Jeff King
2018-08-31  9:58       ` Johannes Schindelin
2018-08-31 15:33         ` Junio C Hamano
2018-08-31 19:47           ` Jeff King
2018-08-31 21:39             ` Junio C Hamano
2018-08-31 21:14           ` Johannes Schindelin
2018-08-31 21:41             ` Jeff King
2018-08-31 21:55               ` Junio C Hamano
2018-08-30  7:09   ` [PATCH 3/5] patch-delta: fix oob read Jeff King
2018-08-30  7:10   ` [PATCH 4/5] patch-delta: consistently report corruption Jeff King
2018-08-30  7:12   ` [PATCH 5/5] patch-delta: handle truncated copy parameters Jeff King
2018-08-30 13:25   ` [PATCH 0/5] handle corruption in patch-delta Jann Horn
2018-08-30 15:23   ` Nicolas Pitre

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