From 3d035f580699feba352f8703cced127fc203f0dd Mon Sep 17 00:00:00 2001 From: Prarit Bhargava Date: Tue, 12 Nov 2013 15:08:33 -0800 Subject: drivers/char/hpet.c: allow user controlled mmap for user processes The CONFIG_HPET_MMAP Kconfig option exposes the memory map of the HPET registers to userspace. The Kconfig help points out that in some cases this can be a security risk as some systems may erroneously configure the map such that additional data is exposed to userspace. This is a problem for distributions -- some users want the MMAP functionality but it comes with a significant security risk. In an effort to mitigate this risk, and due to the low number of users of the MMAP functionality, I've introduced a kernel parameter, hpet_mmap_enable, that is required in order to actually have the HPET MMAP exposed. Signed-off-by: Prarit Bhargava Acked-by: Matt Wilson Signed-off-by: Clemens Ladisch Cc: Randy Dunlap Cc: Tomas Winkler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 882a40d405c8..9ca3e74a10e1 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1070,6 +1070,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. VIA, nVidia) verbose: show contents of HPET registers during setup + hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET + registers. Default set by CONFIG_HPET_MMAP_DEFAULT. + hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. On x86-64 and powerpc, this option can be specified -- cgit v1.2.3