Commit 4c30c6f566c0 ("kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon") added a check on keep_bootcon to ensure that boot consoles were kept around until the real console is registered. This can lead to problems if the boot console data and code are in the init section, since it can be freed before the boot console is deregistered. This was fixed by commit 81cc26f2bd11 ("printk: only unregister boot consoles when necessary"). The keep_bootcon flag prevents the unregistration of a boot console, even if it's data and code reside in the init section and are about to be freed. This can lead to crashes and weird panics when the bootconsole is accessed after free, especially if page poisoning is in use and the code / data have been overwritten with a poison value. To prevent this, always free the boot console if it is within the init section.
Fixes 81cc26f2bd11 ("printk: only unregister boot consoles when necessary"). Signed-off-by: Matt Redfearn <matt.redfe...@imgtec.com> --- kernel/printk/printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a1db38abac5b..b5411f44eed4 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2660,7 +2660,7 @@ static int __init printk_late_init(void) int ret; for_each_console(con) { - if (!keep_bootcon && con->flags & CON_BOOT) { + if (con->flags & CON_BOOT) { /* * Make sure to unregister boot consoles whose data * resides in the init section before the init section -- 2.7.4