From: Jerry James <loganjerry@gmail.com>
Date: Sat, 23 Jun 2018 20:49:04 +0000 (+0200)
Subject: kconfig: loop boundary condition fix
X-Git-Url: https://jxself.org/git/?a=commitdiff_plain;h=c38004b50bcc9378ad1981165dc8dfbb3445c0a9;p=carl9170fw.git

kconfig: loop boundary condition fix

If buf[-1] just happens to hold the byte 0x0A, then nread can wrap around
to (size_t)-1, leading to invalid memory accesses.

This has caused segmentation faults when trying to build the latest
kernel snapshots for i686 in Fedora:
https://bugzilla.redhat.com/show_bug.cgi?id=1592374

Signed-off-by: Jerry James <loganjerry@gmail.com>
[alexpl@fedoraproject.org: reformatted patch for submission]
Signed-off-by: Alexander Ploumistos <alexpl@fedoraproject.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---

diff --git a/config/preprocess.c b/config/preprocess.c
index 65da87f..5ca2df7 100644
--- a/config/preprocess.c
+++ b/config/preprocess.c
@@ -156,7 +156,7 @@ static char *do_shell(int argc, char *argv[])
 		nread--;
 
 	/* remove trailing new lines */
-	while (buf[nread - 1] == '\n')
+	while (nread > 0 && buf[nread - 1] == '\n')
 		nread--;
 
 	buf[nread] = 0;