linux-ext4 - Re: [sparc64] sigbus in e2fsck

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 30 Aug 2016 14:56:45 +0200
From:   John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To:     Anatoly Pugachev <matorola@...il.com>, linux-ext4@...r.kernel.org
Cc:     debian-sparc <debian-sparc@...ts.debian.org>
Subject: Re: [sparc64] sigbus in e2fsck

On 08/30/2016 02:42 PM, Anatoly Pugachev wrote:
> ../../e2fsck/recovery.c:866
> 866                             blocknr = ext2fs_be64_to_cpu(* ((__u64
> *) (bh->b_data+offset)));

The reason is that this expression is casting "char * b_data" [1] into u64 [2]
which provokes unaligned access. Since such expression are often inevitable,
it's probably best to modify the conversion macros in bitops.h [3] to be
safe against unaligned accesses.

An example for that can be seen in the systemd code base [4].

Thanks,
Adrian

> [1] http://lxr.free-electrons.com/source/include/linux/buffer_head.h#L69
> [2] http://git.kernel.org/cgit/fs/ext2/e2fsprogs.git/tree/e2fsck/recovery.c#n866
> [3] http://git.kernel.org/cgit/fs/ext2/e2fsprogs.git/tree/lib/ext2fs/bitops.h
> [4] https://github.com/systemd/systemd/blob/master/src/basic/unaligned.h

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@...ian.org
`. `'   Freie Universitaet Berlin - glaubitz@...sik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html