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From: John Ogness <john.ogness@linutronix.de>
Date: Wed, 20 Sep 2023 17:58:38 +0206
Subject: [PATCH 083/134] printk: fix illegal pbufs access for !CONFIG_PRINTK
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
When CONFIG_PRINTK is not set, PRINTK_MESSAGE_MAX is 0. This
leads to a zero-sized array @outbuf in @printk_shared_pbufs. In
console_flush_all() a pointer to the first element of the array
is assigned with:
char *outbuf = &printk_shared_pbufs.outbuf[0];
For !CONFIG_PRINTK this leads to a compiler warning:
warning: array subscript 0 is outside array bounds of
'char[0]' [-Warray-bounds]
This is not really dangerous because printk_get_next_message()
always returns false for !CONFIG_PRINTK, which leads to @outbuf
never being used. However, it makes no sense to even compile
these functions for !CONFIG_PRINTK.
Extend the existing '#ifdef CONFIG_PRINTK' block to contain
the formatting and emitting functions since these have no
purpose in !CONFIG_PRINTK. This also allows removing several
more !CONFIG_PRINTK dummies as well as moving
@suppress_panic_printk into a CONFIG_PRINTK block.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202309201724.M9BMAQIh-lkp@intel.com/
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230920155238.670439-1-john.ogness@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/printk/printk.c | 44 ++++++++++++++++++--------------------------
1 file changed, 18 insertions(+), 26 deletions(-)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -102,12 +102,6 @@ DEFINE_STATIC_SRCU(console_srcu);
*/
int __read_mostly suppress_printk;
-/*
- * During panic, heavy printk by other CPUs can delay the
- * panic and risk deadlock on console resources.
- */
-static int __read_mostly suppress_panic_printk;
-
#ifdef CONFIG_LOCKDEP
static struct lockdep_map console_lock_dep_map = {
.name = "console_lock"
@@ -445,6 +439,12 @@ static int console_msg_format = MSG_FORM
static DEFINE_MUTEX(syslog_lock);
#ifdef CONFIG_PRINTK
+/*
+ * During panic, heavy printk by other CPUs can delay the
+ * panic and risk deadlock on console resources.
+ */
+static int __read_mostly suppress_panic_printk;
+
DECLARE_WAIT_QUEUE_HEAD(log_wait);
/* All 3 protected by @syslog_lock. */
/* the next printk record to read by syslog(READ) or /proc/kmsg */
@@ -2346,22 +2346,6 @@ static bool __pr_flush(struct console *c
static u64 syslog_seq;
-static size_t record_print_text(const struct printk_record *r,
- bool syslog, bool time)
-{
- return 0;
-}
-static ssize_t info_print_ext_header(char *buf, size_t size,
- struct printk_info *info)
-{
- return 0;
-}
-static ssize_t msg_print_ext_body(char *buf, size_t size,
- char *text, size_t text_len,
- struct dev_printk_info *dev_info) { return 0; }
-static void console_lock_spinning_enable(void) { }
-static int console_lock_spinning_disable_and_check(int cookie) { return 0; }
-static bool suppress_message_printing(int level) { return false; }
static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; }
static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; }
@@ -2715,6 +2699,8 @@ static void __console_unlock(void)
up_console_sem();
}
+#ifdef CONFIG_PRINTK
+
/*
* Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This
* is achieved by shifting the existing message over and inserting the dropped
@@ -2729,7 +2715,6 @@ static void __console_unlock(void)
*
* If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated.
*/
-#ifdef CONFIG_PRINTK
void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
{
struct printk_buffers *pbufs = pmsg->pbufs;
@@ -2761,9 +2746,6 @@ void console_prepend_dropped(struct prin
memcpy(outbuf, scratchbuf, len);
pmsg->outbuf_len += len;
}
-#else
-#define console_prepend_dropped(pmsg, dropped)
-#endif /* CONFIG_PRINTK */
/*
* Read and format the specified record (or a later record if the specified
@@ -2921,6 +2903,16 @@ static bool console_emit_next_record(str
return true;
}
+#else
+
+static bool console_emit_next_record(struct console *con, bool *handover, int cookie)
+{
+ *handover = false;
+ return false;
+}
+
+#endif /* CONFIG_PRINTK */
+
/*
* Print out all remaining records to all consoles.
*
|
