From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Andre Przywara <andre.przywara@arm.com>
Date: Mon, 21 Sep 2020 17:52:50 +0100
Subject: [PATCH] FROMGIT: libfdt: fdt_offset_ptr(): Fix comparison warnings

With -Wsign-compare, compilers warn about mismatching signedness in
comparisons in fdt_offset_ptr().

This mostly stems from "offset" being passed in as a signed integer,
even though the function would not really tolerate negative values.

Short of changing the prototype, check that offset is not negative, and
use an unsigned type internally.

Bug: 230794395
Test: manual - see bug
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Message-Id: <20200921165303.9115-2-andre.przywara@arm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Change-Id: I33c4ac27780d6bdd46c5504a839c0827c9c76bfc
Merged-In: Idb30ae90e2b263d1dd2e931ef1d3662a23812120
Merged-In: Ice02ecc84d6e9ab30773d039a54664b259979521
(cherry picked from commit 35c4c2b27acf66c217865451eeecf09bc82dae66)
Merged-In: I33c4ac27780d6bdd46c5504a839c0827c9c76bfc
---
 libfdt/fdt.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/libfdt/fdt.c b/libfdt/fdt.c
index 22286a1..5baaed3 100644
--- a/libfdt/fdt.c
+++ b/libfdt/fdt.c
@@ -76,15 +76,19 @@ int fdt_check_header(const void *fdt)
 
 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
 {
-	unsigned absoffset = offset + fdt_off_dt_struct(fdt);
+	unsigned int uoffset = offset;
+	unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
 
-	if ((absoffset < offset)
+	if (offset < 0)
+		return NULL;
+
+	if ((absoffset < uoffset)
 	    || ((absoffset + len) < absoffset)
 	    || (absoffset + len) > fdt_totalsize(fdt))
 		return NULL;
 
 	if (fdt_version(fdt) >= 0x11)
-		if (((offset + len) < offset)
+		if (((uoffset + len) < uoffset)
 		    || ((offset + len) > fdt_size_dt_struct(fdt)))
 			return NULL;
 
