From b763ec17ac762470eec5be8ebcc43e4f8b2c2b82 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Sat, 19 Sep 2015 07:00:18 -0700 Subject: regmap: debugfs: Ensure we don't underflow when printing access masks If a read is attempted which is smaller than the line length then we may underflow the subtraction we're doing with the unsigned size_t type so move some of the calculation to be additions on the right hand side instead in order to avoid this. Reported-by: Rasmus Villemoes Signed-off-by: Mark Brown Cc: stable@vger.kernel.org --- drivers/base/regmap/regmap-debugfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c index f42f2bac6466..1f327898e53d 100644 --- a/drivers/base/regmap/regmap-debugfs.c +++ b/drivers/base/regmap/regmap-debugfs.c @@ -432,7 +432,7 @@ static ssize_t regmap_access_read_file(struct file *file, /* If we're in the region the user is trying to read */ if (p >= *ppos) { /* ...but not beyond it */ - if (buf_pos >= count - 1 - tot_len) + if (buf_pos + tot_len + 1 >= count) break; /* Format the register */ -- cgit v1.2.3-58-ga151 From 176fc2d5770a0990eebff903ba680d2edd32e718 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Sat, 19 Sep 2015 07:12:34 -0700 Subject: regmap: debugfs: Don't bother actually printing when calculating max length The in kernel snprintf() will conveniently return the actual length of the printed string even if not given an output beffer at all so just do that rather than relying on the user to pass in a suitable buffer, ensuring that we don't need to worry if the buffer was truncated due to the size of the buffer passed in. Reported-by: Rasmus Villemoes Signed-off-by: Mark Brown Cc: stable@vger.kernel.org --- drivers/base/regmap/regmap-debugfs.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c index 1f327898e53d..4c55cfbad19e 100644 --- a/drivers/base/regmap/regmap-debugfs.c +++ b/drivers/base/regmap/regmap-debugfs.c @@ -32,8 +32,7 @@ static DEFINE_MUTEX(regmap_debugfs_early_lock); /* Calculate the length of a fixed format */ static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size) { - snprintf(buf, buf_size, "%x", max_val); - return strlen(buf); + return snprintf(NULL, 0, "%x", max_val); } static ssize_t regmap_name_read_file(struct file *file, -- cgit v1.2.3-58-ga151