| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20170317114348.30215-1-aleksey.makarov@linaro.org>
Date: Fri, 17 Mar 2017 14:43:44 +0300
From: Aleksey Makarov <aleksey.makarov@...aro.org>
To: linux-serial@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Aleksey Makarov <aleksey.makarov@...aro.org>,
Sudeep Holla <sudeep.holla@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Peter Hurley <peter@...leysoftware.com>,
Jiri Slaby <jslaby@...e.com>,
Robin Murphy <robin.murphy@....com>,
Steven Rostedt <rostedt@...dmis.org>,
"Nair, Jayachandran" <Jayachandran.Nair@...ium.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Petr Mladek <pmladek@...e.com>
Subject: [PATCH v6 3/3] printk: fix double printing with earlycon
If a console was specified by ACPI SPCR table _and_ command line
parameters like "console=ttyAMA0" _and_ "earlycon" were specified,
then log messages appear twice.
The root cause is that the code traverses the list of specified
consoles (the `console_cmdline` array) and stops at the first match.
But it may happen that the same console is referred by the elements
of this array twice:
pl011,mmio,0x87e024000000,115200 -- from SPCR
ttyAMA0 -- from command line
but in this case `preferred_console` points to the second entry and
the flag CON_CONSDEV is not set, so bootconsole is not deregistered.
To fix that, split the loop where we search for matching entry of
console_cmdline into three parts that do not intersect:
1) search for braille console
2) check for preferred_console
3) match other entries so that these three parts do not
To to that introduce predicate _braille_is_braille_console() that checks if
its argument is an entry describing a braille console.
Also introduce a macro for_each_console_cmdline() to traverse
the console_cmdline array.
Reported-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
---
v5 -> v6:
- drop v5 and continue to work on v4:
- introduce _braille_is_braille_console(). It helps to split original loop
into three parts: 1) search for braille console, 2) check for
preferred_console, 3) match other entries so that these three parts do not
intersect.
- introduce for_each_console_cmdline() macros to traverse console_cmdline
(Petr Mladek)
kernel/printk/braille.h | 12 ++++++
kernel/printk/printk.c | 104 ++++++++++++++++++++++++++++++++++--------------
2 files changed, 86 insertions(+), 30 deletions(-)
diff --git a/kernel/printk/braille.h b/kernel/printk/braille.h
index 769d771145c8..183aebf6e1dc 100644
--- a/kernel/printk/braille.h
+++ b/kernel/printk/braille.h
@@ -18,6 +18,12 @@ _braille_register_console(struct console *console, struct console_cmdline *c);
int
_braille_unregister_console(struct console *console);
+static inline int
+_braille_is_braille_console(struct console_cmdline *c)
+{
+ return !!c->brl_options;
+}
+
#else
static inline void
@@ -43,6 +49,12 @@ _braille_unregister_console(struct console *console)
return 0;
}
+static inline int
+_braille_is_braille_console(struct console_cmdline *c)
+{
+ return 0;
+}
+
#endif
#endif
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fd752f0c8ef1..ab2433681ca5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -270,6 +270,11 @@ static struct console *exclusive_console;
static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
+#define for_each_console_cmdline(i, c) \
+ for (i = 0, c = console_cmdline; \
+ i < MAX_CMDLINECONSOLES && c->name[0]; \
+ i++, c++)
+
static int preferred_console = -1;
int console_set_on_cmdline;
EXPORT_SYMBOL(console_set_on_cmdline);
@@ -1905,9 +1910,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
* See if this tty is not yet registered, and
* if we have a slot free.
*/
- for (i = 0, c = console_cmdline;
- i < MAX_CMDLINECONSOLES && c->name[0];
- i++, c++) {
+ for_each_console_cmdline(i, c) {
if (strcmp(c->name, name) == 0 && c->index == idx) {
if (!brl_options)
preferred_console = i;
@@ -2383,6 +2386,37 @@ static int __init keep_bootcon_setup(char *str)
early_param("keep_bootcon", keep_bootcon_setup);
+static bool match_console_name(struct console *newcon,
+ struct console_cmdline *c)
+{
+ BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
+ if (strcmp(c->name, newcon->name) != 0)
+ return false;
+ if (newcon->index >= 0 && newcon->index != c->index)
+ return false;
+ if (newcon->index < 0)
+ newcon->index = c->index;
+ return true;
+}
+
+static bool match_console(struct console *newcon, struct console_cmdline *c)
+{
+ if (newcon->match &&
+ newcon->match(newcon, c->name, c->index, c->options) == 0) {
+ newcon->flags |= CON_ENABLED;
+ return true;
+ }
+
+ if (match_console_name(newcon, c)) {
+ if (!newcon->setup || newcon->setup(newcon, c->options) == 0)
+ newcon->flags |= CON_ENABLED;
+
+ return true;
+ }
+
+ return false;
+}
+
/*
* The console driver calls this routine during kernel initialization
* to register the console printing procedure with printk() and to
@@ -2457,40 +2491,50 @@ void register_console(struct console *newcon)
}
/*
- * See if this console matches one we selected on
- * the command line.
+ * See if this console matches one we selected on the command line.
+ * Do it in three steps:
+ *
+ * 1) check if it is a braille console..
*/
- for (i = 0, c = console_cmdline;
- i < MAX_CMDLINECONSOLES && c->name[0];
- i++, c++) {
- if (!newcon->match ||
- newcon->match(newcon, c->name, c->index, c->options) != 0) {
- /* default matching */
- BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
- if (strcmp(c->name, newcon->name) != 0)
- continue;
- if (newcon->index >= 0 &&
- newcon->index != c->index)
- continue;
- if (newcon->index < 0)
- newcon->index = c->index;
-
- if (_braille_register_console(newcon, c))
- return;
-
- if (newcon->setup &&
- newcon->setup(newcon, c->options) != 0)
- break;
- }
+ for_each_console_cmdline(i, c)
+ if (_braille_is_braille_console(c) &&
+ match_console_name(newcon, c) &&
+ _braille_register_console(newcon, c))
+ return;
- newcon->flags |= CON_ENABLED;
- if (i == preferred_console) {
+ /*
+ * 2) check if this console was set as preferred by command line
+ * parameters or by call to add_preferred_console(). There may be
+ * several entries in the console_cmdline array matching with the same
+ * console, one with newcon->match(), another by name/index:
+ *
+ * pl011,mmio,0x87e024000000,115200 -- added from SPCR
+ * ttyAMA0 -- added from command line
+ *
+ * so we can not use the first match. Instead check the
+ * entry pointed by preferred_console and then all other entries.
+ */
+ if (preferred_console >= 0 &&
+ match_console(newcon, console_cmdline + preferred_console)) {
+ if (newcon->flags & CON_ENABLED) {
newcon->flags |= CON_CONSDEV;
has_preferred = true;
}
- break;
+ goto match;
+ }
+
+ /*
+ * 3) check other entries
+ */
+ for_each_console_cmdline(i, c) {
+ if (preferred_console == i || _braille_is_braille_console(c))
+ continue;
+
+ if (match_console(newcon, c))
+ goto match;
}
+match:
if (!(newcon->flags & CON_ENABLED))
return;
--
2.12.0
Powered by blists - more mailing lists