On Sun 2018-12-02 14:02:28, Tetsuo Handa wrote: > On 2018/12/02 8:49, kbuild test robot wrote: > >> kernel/printk/printk.c:2396:5: error: 'printk_time' undeclared (first use > >> in this function) > ^~~~~~~~~~~ > Thanks. printk_time depends on CONFIG_PRINTK=y. Added a dummy definition. > > > > >From f903b9fa36159472a207f93e2405e45e3999f650 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> > Date: Sun, 2 Dec 2018 13:57:01 +0900 > Subject: [PATCH v2] printk: fix printk_time race. > > Since printk_time can be toggled via /sys/module/printk/parameters/time , > it is not safe to assume that output length does not change across > multiple msg_print_text() calls. If we hit this race, we can observe > failures such as SYSLOG_ACTION_READ_ALL writes more bytes than userspace > has supplied, SYSLOG_ACTION_SIZE_UNREAD returns -EFAULT when succeeded, > SYSLOG_ACTION_READ reads garbage memory or even triggers an kernel oops > at _copy_to_user() due to integer overflow. > > To close this race, get a snapshot value of printk_time and pass it to > SYSLOG_ACTION_READ, SYSLOG_ACTION_READ_ALL, SYSLOG_ACTION_SIZE_UNREAD and > kmsg_dump_get_buffer(). > > Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> > Signed-off-by: Petr Mladek <pmla...@suse.com>
The patch looks good to me. Acked-by: Petr Mladek <pmla...@suse.com> I'll wait few more days for an eventual feedback before I push it into printk.git. Best Regards, Petr
