From: Linus Torvalds Date: Wed, 14 May 2014 23:33:54 +0000 (-0700) Subject: x86-64, modify_ldt: Make support for 16-bit segments a runtime option X-Git-Tag: v3.2.60~21 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=434ffe9cc9c9336f375f1acfb00993ee6f18bd80;p=pandora-kernel.git x86-64, modify_ldt: Make support for 16-bit segments a runtime option commit fa81511bb0bbb2b1aace3695ce869da9762624ff upstream. Checkin: b3b42ac2cbae x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels disabled 16-bit segments on 64-bit kernels due to an information leak. However, it does seem that people are genuinely using Wine to run old 16-bit Windows programs on Linux. A proper fix for this ("espfix64") is coming in the upcoming merge window, but as a temporary fix, create a sysctl to allow the administrator to re-enable support for 16-bit segments. It adds a "/proc/sys/abi/ldt16" sysctl that defaults to zero (off). If you hit this issue and care about your old Windows program more than you care about a kernel stack address information leak, you can do echo 1 > /proc/sys/abi/ldt16 as root (add it to your startup scripts), and you should be ok. The sysctl table is only added if you have COMPAT support enabled on x86-64, but I assume anybody who runs old windows binaries very much does that ;) Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/CA%2B55aFw9BPoD10U1LfHbOMpHWZkvJTkMcfCs9s3urPr1YyWBxw@mail.gmail.com Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed