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authorPrarit Bhargava <prarit@redhat.com>2013-11-12 15:08:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-13 12:09:11 +0900
commit3d035f580699feba352f8703cced127fc203f0dd (patch)
tree9469709ea2eda88e66531edb865ab41757615a0d /Documentation
parent72403b4a0fbdf433c1fe0127e49864658f6f6468 (diff)
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 <prarit@redhat.com> Acked-by: Matt Wilson <msw@amazon.com> Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 882a40d405c..9ca3e74a10e 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