From 2b87f3aac04818f720956e2b70f9b04fc8e2c794 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 14 May 2010 15:24:37 +0200 Subject: [PATCH] ath9k/debug: improve the snprintf() handling The snprintf() function returns the number of bytes that *would* have been written (not counting the NULL terminator) and that can potentally be more than the size of the buffer. In this patch if there were one liners where string clearly fits into the buffer, then I changed snprintf to sprintf(). It's confusing to use the return value of snprintf() as a limitter without verifying that it's smaller than size. This is what initially caught my attention here. If we use the return value of sprintf() instead future code auditors will assume we've verified that it fits already. Also I did find some places where it made sense to use the return value after we've verified that it is smaller than the buffer size. Finally the read_file_rcstat() function added an explicit NULL terminator before calling snprintf(). That's unnecessary because snprintf() will add the null terminator automatically. Signed-off-by: Dan Carpenter Signed-off-by: John W. Linville --- drivers/net/wireless/ath/ath9k/debug.c | 33 +++++++++++++++++++------- 1 file changed, 25 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/ath/ath9k/debug.c b/drivers/net/wireless/ath/ath9k/debug.c index ee8387740ebe..ad7107164f20 100644 --- a/drivers/net/wireless/ath/ath9k/debug.c +++ b/drivers/net/wireless/ath/ath9k/debug.c @@ -42,7 +42,7 @@ static ssize_t read_file_debug(struct file *file, char __user *user_buf, char buf[32]; unsigned int len; - len = snprintf(buf, sizeof(buf), "0x%08x\n", common->debug_mask); + len = sprintf(buf, "0x%08x\n", common->debug_mask); return simple_read_from_buffer(user_buf, count, ppos, buf, len); } @@ -86,7 +86,7 @@ static ssize_t read_file_tx_chainmask(struct file *file, char __user *user_buf, char buf[32]; unsigned int len; - len = snprintf(buf, sizeof(buf), "0x%08x\n", common->tx_chainmask); + len = sprintf(buf, "0x%08x\n", common->tx_chainmask); return simple_read_from_buffer(user_buf, count, ppos, buf, len); } @@ -128,7 +128,7 @@ static ssize_t read_file_rx_chainmask(struct file *file, char __user *user_buf, char buf[32]; unsigned int len; - len = snprintf(buf, sizeof(buf), "0x%08x\n", common->rx_chainmask); + len = sprintf(buf, "0x%08x\n", common->rx_chainmask); return simple_read_from_buffer(user_buf, count, ppos, buf, len); } @@ -248,6 +248,9 @@ static ssize_t read_file_dma(struct file *file, char __user *user_buf, ath9k_ps_restore(sc); + if (len > DMA_BUF_LEN) + len = DMA_BUF_LEN; + retval = simple_read_from_buffer(user_buf, count, ppos, buf, len); kfree(buf); return retval; @@ -363,6 +366,9 @@ static ssize_t read_file_interrupt(struct file *file, char __user *user_buf, len += snprintf(buf + len, sizeof(buf) - len, "%8s: %10u\n", "TOTAL", sc->debug.stats.istats.total); + if (len > sizeof(buf)) + len = sizeof(buf); + return simple_read_from_buffer(user_buf, count, ppos, buf, len); } @@ -402,11 +408,10 @@ static ssize_t read_file_rcstat(struct file *file, char __user *user_buf, if (sc->cur_rate_table == NULL) return 0; - max = 80 + sc->cur_rate_table->rate_cnt * 1024; - buf = kmalloc(max + 1, GFP_KERNEL); + max = 80 + sc->cur_rate_table->rate_cnt * 1024 + 1; + buf = kmalloc(max, GFP_KERNEL); if (buf == NULL) return 0; - buf[max] = 0; len += sprintf(buf, "%6s %6s %6s " "%10s %10s %10s %10s\n", @@ -448,6 +453,9 @@ static ssize_t read_file_rcstat(struct file *file, char __user *user_buf, stats->per); } + if (len > max) + len = max; + retval = simple_read_from_buffer(user_buf, count, ppos, buf, len); kfree(buf); return retval; @@ -510,6 +518,9 @@ static ssize_t read_file_wiphy(struct file *file, char __user *user_buf, len += snprintf(buf + len, sizeof(buf) - len, "addrmask: %pM\n", addr); + if (len > sizeof(buf)) + len = sizeof(buf); + return simple_read_from_buffer(user_buf, count, ppos, buf, len); } @@ -653,6 +664,9 @@ static ssize_t read_file_xmit(struct file *file, char __user *user_buf, PR("DATA Underrun: ", data_underrun); PR("DELIM Underrun: ", delim_underrun); + if (len > size) + len = size; + retval = simple_read_from_buffer(user_buf, count, ppos, buf, len); kfree(buf); @@ -756,6 +770,9 @@ static ssize_t read_file_recv(struct file *file, char __user *user_buf, PHY_ERR("HT-LENGTH", ATH9K_PHYERR_HT_LENGTH_ILLEGAL); PHY_ERR("HT-RATE", ATH9K_PHYERR_HT_RATE_ILLEGAL); + if (len > size) + len = size; + retval = simple_read_from_buffer(user_buf, count, ppos, buf, len); kfree(buf); @@ -807,7 +824,7 @@ static ssize_t read_file_regidx(struct file *file, char __user *user_buf, char buf[32]; unsigned int len; - len = snprintf(buf, sizeof(buf), "0x%08x\n", sc->debug.regidx); + len = sprintf(buf, "0x%08x\n", sc->debug.regidx); return simple_read_from_buffer(user_buf, count, ppos, buf, len); } @@ -848,7 +865,7 @@ static ssize_t read_file_regval(struct file *file, char __user *user_buf, u32 regval; regval = REG_READ_D(ah, sc->debug.regidx); - len = snprintf(buf, sizeof(buf), "0x%08x\n", regval); + len = sprintf(buf, "0x%08x\n", regval); return simple_read_from_buffer(user_buf, count, ppos, buf, len); } -- 2.34.1