diff options
author | Eric Biggers <ebiggers@google.com> | 2018-11-14 13:55:09 -0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-27 16:05:38 +0100 |
commit | 40e10ccf9fbd8a29e6bdd9d832b67df7000bce1d (patch) | |
tree | eae79ded53752ddab572a284000a905d46ea46c7 /lib/xz | |
parent | 9265b0aba03d6754ddcd6ea8aced431be0380626 (diff) |
HID: uhid: forbid UHID_CREATE under KERNEL_DS or elevated privileges
commit 8c01db7619f07c85c5cd81ec5eb83608b56c88f5 upstream.
When a UHID_CREATE command is written to the uhid char device, a
copy_from_user() is done from a user pointer embedded in the command.
When the address limit is KERNEL_DS, e.g. as is the case during
sys_sendfile(), this can read from kernel memory. Alternatively,
information can be leaked from a setuid binary that is tricked to write
to the file descriptor. Therefore, forbid UHID_CREATE in these cases.
No other commands in uhid_char_write() are affected by this bug and
UHID_CREATE is marked as "obsolete", so apply the restriction to
UHID_CREATE only rather than to uhid_char_write() entirely.
Thanks to Dmitry Vyukov for adding uhid definitions to syzkaller and to
Jann Horn for commit 9da3f2b740544 ("x86/fault: BUG() when uaccess
helpers fault on kernel addresses"), allowing this bug to be found.
Reported-by: syzbot+72473edc9bf4eb1c6556@syzkaller.appspotmail.com
Fixes: d365c6cfd337 ("HID: uhid: add UHID_CREATE and UHID_DESTROY events")
Cc: <stable@vger.kernel.org> # v3.6+
Cc: Jann Horn <jannh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib/xz')
0 files changed, 0 insertions, 0 deletions