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printk: fix return value of printk.devkmsg __setup handler 

[ Upstream commit b665eae7a7 ]

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: 750afe7bab ("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>
This commit is contained in:
Randy Dunlap 2022-02-28 14:05:56 -08:00 committed by Greg Kroah-Hartman
parent ed73769ab8
commit f64b0e4547
1 changed files with 4 additions and 2 deletions
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6
kernel/printk/printk.c
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@ -122,8 +122,10 @@ 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:
@ -145,7 +147,7 @@ static int __init control_devkmsg(char *str)
*/
devkmsg_log |= DEVKMSG_LOG_MASK_LOCK;
return 0;
return 1;
}
__setup("printk.devkmsg=", control_devkmsg);