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Date: Wed, 11 Jul 2012 14:20:27 +0100 From: Gordan Bobic <gordan@...ich.net> To: linux-ext4@...r.kernel.org Subject: e2fsprogs alignment issues I would like to bring the following bug report to people's attention: https://bugzilla.redhat.com/show_bug.cgi?id=680090 The issue is that the code used in e2fsprogs WRT allocating unaligned buffers and then casting them into structs is non-portable and dangerous - eyewateringly dangerous in something like e2fsprogs where it can lead to thorough trashing of the file system. Can something be done to improve the portability of the userspace code? The issue has been discussed on the Fedora-ARM mailing list: http://lists.fedoraproject.org/pipermail/arm/2012-July/003637.html but the argument there was that the issue needs to be fixed upstream, hence why I am posting it here. This is an issue on all ARMs up to ARMv5, possibly ARMv6, and likely other CPU architectures that don't have transparent alignment fixup in hardware (Itanium, SPARC, probably others). Apart from being dangerous, using unaligned arrays also affects performance because it leads to data needlessly straddling cache lines in the CPU. But that doesn't really matter in this case. Many thanks. Gordan -- 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
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