From: Mark Brown Date: Mon, 10 Dec 2012 16:14:11 +0000 (+0900) Subject: regmap: debugfs: Avoid overflows for very small reads X-Git-Tag: v3.7.3~103 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1b766177ea25e0fca2beffbde9bc82bdb763d1bc;p=thirdparty%2Fkernel%2Fstable.git regmap: debugfs: Avoid overflows for very small reads commit db04328c167ff8e7c57f4a3532214aeada3a82fd upstream. 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c index bb1ff175b9629..c39404167dc85 100644 --- a/drivers/base/regmap/regmap-debugfs.c +++ b/drivers/base/regmap/regmap-debugfs.c @@ -90,7 +90,7 @@ static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf, /* 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 + 1 + tot_len >= count) break; /* Format the register */