]> git.baikalelectronics.ru Git - kernel.git/commit
x86/tls: Disallow unusual TLS segments
authorAndy Lutomirski <luto@amacapital.net>
Fri, 5 Dec 2014 00:48:17 +0000 (16:48 -0800)
committerIngo Molnar <mingo@kernel.org>
Sun, 14 Dec 2014 07:50:31 +0000 (08:50 +0100)
commit9b835cb942f60ac9d7c0e7dde95d020602148f79
treec0c467ac8bb54409c38026f0c925f4a57a8bdc0f
parent37717d494913383248bf6aedd708e7e4cfc8314a
x86/tls: Disallow unusual TLS segments

Users have no business installing custom code segments into the
GDT, and segments that are not present but are otherwise valid
are a historical source of interesting attacks.

For completeness, block attempts to set the L bit.  (Prior to
this patch, the L bit would have been silently dropped.)

This is an ABI break.  I've checked glibc, musl, and Wine, and
none of them look like they'll have any trouble.

Note to stable maintainers: this is a hardening patch that fixes
no known bugs.  Given the possibility of ABI issues, this
probably shouldn't be backported quickly.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: stable@vger.kernel.org # optional
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: security@kernel.org <security@kernel.org>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/tls.c