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printk: fix illegal pbufs access for !CONFIG_PRINTK
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
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@ -102,12 +102,6 @@ DEFINE_STATIC_SRCU(console_srcu);
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*/
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int __read_mostly suppress_printk;
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/*
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* During panic, heavy printk by other CPUs can delay the
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* panic and risk deadlock on console resources.
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*/
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static int __read_mostly suppress_panic_printk;
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#ifdef CONFIG_LOCKDEP
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static struct lockdep_map console_lock_dep_map = {
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.name = "console_lock"
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@ -445,6 +439,12 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
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static DEFINE_MUTEX(syslog_lock);
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#ifdef CONFIG_PRINTK
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/*
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* During panic, heavy printk by other CPUs can delay the
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* panic and risk deadlock on console resources.
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*/
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static int __read_mostly suppress_panic_printk;
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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/* All 3 protected by @syslog_lock. */
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/* the next printk record to read by syslog(READ) or /proc/kmsg */
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@ -2346,22 +2346,6 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
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static u64 syslog_seq;
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static size_t record_print_text(const struct printk_record *r,
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bool syslog, bool time)
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{
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return 0;
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}
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static ssize_t info_print_ext_header(char *buf, size_t size,
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struct printk_info *info)
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{
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return 0;
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}
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static ssize_t msg_print_ext_body(char *buf, size_t size,
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char *text, size_t text_len,
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struct dev_printk_info *dev_info) { return 0; }
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static void console_lock_spinning_enable(void) { }
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static int console_lock_spinning_disable_and_check(int cookie) { return 0; }
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static bool suppress_message_printing(int level) { return false; }
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static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; }
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static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; }
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@ -2715,6 +2699,8 @@ static void __console_unlock(void)
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up_console_sem();
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}
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#ifdef CONFIG_PRINTK
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/*
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* Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This
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* is achieved by shifting the existing message over and inserting the dropped
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@ -2729,7 +2715,6 @@ static void __console_unlock(void)
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*
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* If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated.
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*/
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#ifdef CONFIG_PRINTK
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void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
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{
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struct printk_buffers *pbufs = pmsg->pbufs;
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@ -2761,9 +2746,6 @@ void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
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memcpy(outbuf, scratchbuf, len);
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pmsg->outbuf_len += len;
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}
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#else
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#define console_prepend_dropped(pmsg, dropped)
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#endif /* CONFIG_PRINTK */
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/*
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* Read and format the specified record (or a later record if the specified
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@ -2921,6 +2903,16 @@ skip:
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return true;
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}
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#else
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static bool console_emit_next_record(struct console *con, bool *handover, int cookie)
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{
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*handover = false;
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return false;
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}
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#endif /* CONFIG_PRINTK */
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/*
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* Print out all remaining records to all consoles.
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*
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