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| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | 2010-02-25 22:22:22 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-26 07:41:22 -0700 |
| commit | 1b0d63f15fb79d0cb840f8b701f343548b5640e8 (patch) | |
| tree | 13544b47f91370a4d7be8d96a4801bcd26d11071 /Documentation | |
| parent | a772b90083481bd87458f48641dd7ba9e2401393 (diff) | |
| download | lwn-1b0d63f15fb79d0cb840f8b701f343548b5640e8.tar.gz lwn-1b0d63f15fb79d0cb840f8b701f343548b5640e8.zip | |
thinkpad-acpi: lock down video output state access
commit b525c06cdbd8a3963f0173ccd23f9147d4c384b5 upstream.
Given the right combination of ThinkPad and X.org, just reading the
video output control state is enough to hard-crash X.org.
Until the day I somehow find out a model or BIOS cut date to not
provide this feature to ThinkPads that can do video switching through
X RandR, change permissions so that only processes with CAP_SYS_ADMIN
can access any sort of video output control state.
This bug could be considered a local DoS I suppose, as it allows any
non-privledged local user to cause some versions of X.org to
hard-crash some ThinkPads.
Reported-by: Jidanni <jidanni@jidanni.org>
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/laptops/thinkpad-acpi.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt index f5056c7fb5be..387eb9c6bf5d 100644 --- a/Documentation/laptops/thinkpad-acpi.txt +++ b/Documentation/laptops/thinkpad-acpi.txt @@ -650,6 +650,10 @@ LCD, CRT or DVI (if available). The following commands are available: echo expand_toggle > /proc/acpi/ibm/video echo video_switch > /proc/acpi/ibm/video +NOTE: Access to this feature is restricted to processes owning the +CAP_SYS_ADMIN capability for safety reasons, as it can interact badly +enough with some versions of X.org to crash it. + Each video output device can be enabled or disabled individually. Reading /proc/acpi/ibm/video shows the status of each device. |