From: Randy Dunlap rdunlap@infradead.org
[ Upstream commit b665eae7a788c5e2bc10f9ac3c0137aa0ad1fc97 ]
If an invalid option value is used with "printk.devkmsg=<value>", it is silently ignored. If a valid option value is used, it is honored but the wrong return value (0) is used, indicating that the command line option had an error and was not handled. This string is not added to init's environment strings due to init/main.c::unknown_bootoption() checking for a '.' in the boot option string and then considering that string to be an "Unused module parameter".
Print a warning message if a bad option string is used. Always return 1 from the __setup handler to indicate that the command line option has been handled.
Fixes: 750afe7babd1 ("printk: add kernel parameter to control writes to /dev/kmsg") Signed-off-by: Randy Dunlap rdunlap@infradead.org Reported-by: Igor Zhbanov i.zhbanov@omprussia.ru Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Cc: Borislav Petkov bp@suse.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Petr Mladek pmladek@suse.com Cc: Sergey Senozhatsky senozhatsky@chromium.org Cc: Steven Rostedt rostedt@goodmis.org Cc: John Ogness john.ogness@linutronix.de Reviewed-by: John Ogness john.ogness@linutronix.de Reviewed-by: Sergey Senozhatsky senozhatsky@chromium.org Reviewed-by: Petr Mladek pmladek@suse.com Signed-off-by: Petr Mladek pmladek@suse.com Link: https://lore.kernel.org/r/20220228220556.23484-1-rdunlap@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/printk/printk.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 31b5e7919d62..11173d0b51bc 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -125,8 +125,10 @@ static int __control_devkmsg(char *str)
static int __init control_devkmsg(char *str) { - if (__control_devkmsg(str) < 0) + if (__control_devkmsg(str) < 0) { + pr_warn("printk.devkmsg: bad option string '%s'\n", str); return 1; + }
/* * Set sysctl string accordingly: @@ -148,7 +150,7 @@ static int __init control_devkmsg(char *str) */ devkmsg_log |= DEVKMSG_LOG_MASK_LOCK;
- return 0; + return 1; } __setup("printk.devkmsg=", control_devkmsg);