regmap: debugfs: Avoid overflows for very small reads
If count is less than the size of a register then we may hit integer
wraparound when trying to move backwards to check if we're still in
the buffer. Instead move the position forwards to check if it's still
in the buffer, we are unlikely to be able to allocate a buffer
sufficiently big to overflow here.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 00fbd58..3df274e 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -93,7 +93,7 @@
/* If we're in the region the user is trying to read */
if (p >= *ppos) {
/* ...but not beyond it */
- if (buf_pos >= count - 1 - map->debugfs_tot_len)
+ if (buf_pos + 1 + map->debugfs_tot_len >= count)
break;
/* Format the register */