mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-08-09 06:14:34 +02:00
Pengpeng HouandAndreas Larsson
7eb475e8a7
led_proc_write() duplicates up to LED_MAX_LENGTH bytes with
memdup_user_nul() and then unconditionally inspects buf[count - 1] to
strip a trailing newline. A zero-length write therefore reads one byte
before the duplicated buffer.
The previous version rejected empty writes, but empty input already falls
through to the existing default case and turns the LED off like any other
unrecognized string. Preserve that behavior and only skip the newline
trim when there is no input byte to inspect.
Fixes: ee1858d312 ("[SPARC]: Add sun4m LED driver.")
Suggested-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
147 lines
3.2 KiB
C
147 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/jiffies.h>
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#include <linux/timer.h>
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#include <linux/uaccess.h>
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#include <linux/sched/loadavg.h>
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#include <asm/auxio.h>
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#define LED_MAX_LENGTH 8 /* maximum chars written to proc file */
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static inline void led_toggle(void)
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{
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unsigned char val = get_auxio();
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unsigned char on, off;
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if (val & AUXIO_LED) {
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on = 0;
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off = AUXIO_LED;
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} else {
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on = AUXIO_LED;
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off = 0;
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}
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set_auxio(on, off);
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}
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static struct timer_list led_blink_timer;
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static unsigned long led_blink_timer_timeout;
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static void led_blink(struct timer_list *unused)
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{
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unsigned long timeout = led_blink_timer_timeout;
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led_toggle();
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/* reschedule */
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if (!timeout) { /* blink according to load */
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led_blink_timer.expires = jiffies +
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((1 + (avenrun[0] >> FSHIFT)) * HZ);
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} else { /* blink at user specified interval */
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led_blink_timer.expires = jiffies + (timeout * HZ);
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}
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add_timer(&led_blink_timer);
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}
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#ifdef CONFIG_PROC_FS
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static int led_proc_show(struct seq_file *m, void *v)
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{
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if (get_auxio() & AUXIO_LED)
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seq_puts(m, "on\n");
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else
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seq_puts(m, "off\n");
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return 0;
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}
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static int led_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, led_proc_show, NULL);
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}
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static ssize_t led_proc_write(struct file *file, const char __user *buffer,
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size_t count, loff_t *ppos)
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{
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char *buf = NULL;
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if (count > LED_MAX_LENGTH)
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count = LED_MAX_LENGTH;
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buf = memdup_user_nul(buffer, count);
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if (IS_ERR(buf))
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return PTR_ERR(buf);
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/* work around \n when echo'ing into proc */
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if (count > 0 && buf[count - 1] == '\n')
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buf[count - 1] = '\0';
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/* before we change anything we want to stop any running timers,
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* otherwise calls such as on will have no persistent effect
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*/
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timer_delete_sync(&led_blink_timer);
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if (!strcmp(buf, "on")) {
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auxio_set_led(AUXIO_LED_ON);
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} else if (!strcmp(buf, "toggle")) {
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led_toggle();
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} else if ((*buf > '0') && (*buf <= '9')) {
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led_blink_timer_timeout = simple_strtoul(buf, NULL, 10);
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led_blink(&led_blink_timer);
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} else if (!strcmp(buf, "load")) {
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led_blink_timer_timeout = 0;
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led_blink(&led_blink_timer);
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} else {
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auxio_set_led(AUXIO_LED_OFF);
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}
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kfree(buf);
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return count;
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}
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static const struct proc_ops led_proc_ops = {
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.proc_open = led_proc_open,
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.proc_read = seq_read,
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.proc_lseek = seq_lseek,
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.proc_release = single_release,
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.proc_write = led_proc_write,
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};
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#endif
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#define LED_VERSION "0.1"
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static int __init led_init(void)
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{
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timer_setup(&led_blink_timer, led_blink, 0);
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#ifdef CONFIG_PROC_FS
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if (!proc_create("led", 0, NULL, &led_proc_ops))
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return -ENOMEM;
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#endif
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printk(KERN_INFO
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"led: version %s, Lars Kotthoff <metalhead@metalhead.ws>\n",
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LED_VERSION);
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return 0;
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}
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static void __exit led_exit(void)
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{
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remove_proc_entry("led", NULL);
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timer_delete_sync(&led_blink_timer);
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}
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module_init(led_init);
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module_exit(led_exit);
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MODULE_AUTHOR("Lars Kotthoff <metalhead@metalhead.ws>");
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MODULE_DESCRIPTION("Provides control of the front LED on SPARC systems.");
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MODULE_LICENSE("GPL");
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MODULE_VERSION(LED_VERSION);
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