From 98d408f654044f497834ce0f7336603b3902fe21 Mon Sep 17 00:00:00 2001 From: Ankit Sharma Date: Thu, 19 Jan 2017 20:22:14 +0530 Subject: [PATCH] leds: qpnp-flash: Fix possible race condition in debugfs There is a possible race condition when debugfs files are concurrently accessed by multiple threads. Fix this. CRs-Fixed: 1109420, 1109326 Change-Id: I19e9107079ac8d039b12a37ae612727f824552d4 Signed-off-by: Ankit Sharma --- drivers/leds/leds-qpnp-flash.c | 78 ++++++++++++++++++++++++---------- 1 file changed, 56 insertions(+), 22 deletions(-) diff --git a/drivers/leds/leds-qpnp-flash.c b/drivers/leds/leds-qpnp-flash.c index c27c0593cd10..cd76941b87ca 100644 --- a/drivers/leds/leds-qpnp-flash.c +++ b/drivers/leds/leds-qpnp-flash.c @@ -226,6 +226,7 @@ struct flash_led_platform_data { }; struct qpnp_flash_led_buffer { + struct mutex debugfs_lock; /* Prevent thread concurrency */ size_t rpos; size_t wpos; size_t len; @@ -282,6 +283,7 @@ static int flash_led_dbgfs_file_open(struct qpnp_flash_led *led, log->rpos = 0; log->wpos = 0; log->len = logbufsize - sizeof(*log); + mutex_init(&log->debugfs_lock); led->log = log; led->buffer_cnt = 1; @@ -303,20 +305,26 @@ static int flash_led_dfs_close(struct inode *inode, struct file *file) if (led && led->log) { file->private_data = NULL; + mutex_destroy(&led->log->debugfs_lock); kfree(led->log); } return 0; } +#define MIN_BUFFER_WRITE_LEN 20 static int print_to_log(struct qpnp_flash_led_buffer *log, const char *fmt, ...) { va_list args; int cnt; - char *log_buf = &log->data[log->wpos]; + char *log_buf; size_t size = log->len - log->wpos; + if (size < MIN_BUFFER_WRITE_LEN) + return 0; /* not enough buffer left */ + + log_buf = &log->data[log->wpos]; va_start(args, fmt); cnt = vscnprintf(log_buf, size, fmt, args); va_end(args); @@ -330,29 +338,31 @@ static ssize_t flash_led_dfs_latched_reg_read(struct file *fp, char __user *buf, struct qpnp_flash_led *led = fp->private_data; struct qpnp_flash_led_buffer *log = led->log; uint val; - int rc; + int rc = 0; size_t len; size_t ret; - if (log->rpos >= log->wpos && led->buffer_cnt == 0) - return 0; + mutex_lock(&log->debugfs_lock); + if ((log->rpos >= log->wpos && led->buffer_cnt == 0) || + ((log->len - log->wpos) < MIN_BUFFER_WRITE_LEN)) + goto unlock_mutex; rc = regmap_read(led->regmap, INT_LATCHED_STS(led->base), &val); if (rc) { dev_err(&led->pdev->dev, "Unable to read from address %x, rc(%d)\n", INT_LATCHED_STS(led->base), rc); - return -EINVAL; + goto unlock_mutex; } led->buffer_cnt--; rc = print_to_log(log, "0x%05X ", INT_LATCHED_STS(led->base)); if (rc == 0) - return rc; + goto unlock_mutex; rc = print_to_log(log, "0x%02X ", val); if (rc == 0) - return rc; + goto unlock_mutex; if (log->wpos > 0 && log->data[log->wpos - 1] == ' ') log->data[log->wpos - 1] = '\n'; @@ -362,36 +372,43 @@ static ssize_t flash_led_dfs_latched_reg_read(struct file *fp, char __user *buf, ret = copy_to_user(buf, &log->data[log->rpos], len); if (ret) { pr_err("error copy register value to user\n"); - return -EFAULT; + rc = -EFAULT; + goto unlock_mutex; } len -= ret; *ppos += len; log->rpos += len; - return len; + rc = len; + +unlock_mutex: + mutex_unlock(&log->debugfs_lock); + return rc; } static ssize_t flash_led_dfs_fault_reg_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos) { struct qpnp_flash_led *led = fp->private_data; struct qpnp_flash_led_buffer *log = led->log; - int rc; + int rc = 0; size_t len; size_t ret; - if (log->rpos >= log->wpos && led->buffer_cnt == 0) - return 0; + mutex_lock(&log->debugfs_lock); + if ((log->rpos >= log->wpos && led->buffer_cnt == 0) || + ((log->len - log->wpos) < MIN_BUFFER_WRITE_LEN)) + goto unlock_mutex; led->buffer_cnt--; rc = print_to_log(log, "0x%05X ", FLASH_LED_FAULT_STATUS(led->base)); if (rc == 0) - return rc; + goto unlock_mutex; rc = print_to_log(log, "0x%02X ", led->fault_reg); if (rc == 0) - return rc; + goto unlock_mutex; if (log->wpos > 0 && log->data[log->wpos - 1] == ' ') log->data[log->wpos - 1] = '\n'; @@ -401,14 +418,19 @@ static ssize_t flash_led_dfs_fault_reg_read(struct file *fp, char __user *buf, ret = copy_to_user(buf, &log->data[log->rpos], len); if (ret) { pr_err("error copy register value to user\n"); - return -EFAULT; + rc = -EFAULT; + goto unlock_mutex; } len -= ret; *ppos += len; log->rpos += len; - return len; + rc = len; + +unlock_mutex: + mutex_unlock(&log->debugfs_lock); + return rc; } static ssize_t flash_led_dfs_fault_reg_enable(struct file *file, @@ -421,10 +443,14 @@ static ssize_t flash_led_dfs_fault_reg_enable(struct file *file, size_t ret = 0; struct qpnp_flash_led *led = file->private_data; - char *kbuf = kmalloc(count + 1, GFP_KERNEL); + char *kbuf; - if (!kbuf) - return -ENOMEM; + mutex_lock(&led->log->debugfs_lock); + kbuf = kmalloc(count + 1, GFP_KERNEL); + if (!kbuf) { + ret = -ENOMEM; + goto unlock_mutex; + } ret = copy_from_user(kbuf, buf, count); if (!ret) { @@ -453,6 +479,8 @@ static ssize_t flash_led_dfs_fault_reg_enable(struct file *file, free_buf: kfree(kbuf); +unlock_mutex: + mutex_unlock(&led->log->debugfs_lock); return ret; } @@ -465,10 +493,14 @@ static ssize_t flash_led_dfs_dbg_enable(struct file *file, int data; size_t ret = 0; struct qpnp_flash_led *led = file->private_data; - char *kbuf = kmalloc(count + 1, GFP_KERNEL); + char *kbuf; - if (!kbuf) - return -ENOMEM; + mutex_lock(&led->log->debugfs_lock); + kbuf = kmalloc(count + 1, GFP_KERNEL); + if (!kbuf) { + ret = -ENOMEM; + goto unlock_mutex; + } ret = copy_from_user(kbuf, buf, count); if (ret == count) { @@ -496,6 +528,8 @@ static ssize_t flash_led_dfs_dbg_enable(struct file *file, free_buf: kfree(kbuf); +unlock_mutex: + mutex_unlock(&led->log->debugfs_lock); return ret; }