From: Tiwei Bie <tiwei.btw@antgroup.com>
Date: Mon, 16 Sep 2024 04:59:48 +0000 (+0800)
Subject: um: Fix potential integer overflow during physmem setup
X-Git-Tag: v6.13-rc1~18^2~61
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a98b7761f697e590ed5d610d87fa12be66f23419;p=thirdparty%2Fkernel%2Flinux.git

um: Fix potential integer overflow during physmem setup

This issue happens when the real map size is greater than LONG_MAX,
which can be easily triggered on UML/i386.

Fixes: fe205bdd1321 ("um: Print minimum physical memory requirement")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240916045950.508910-3-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index fb2adfb499452..ee693e0b2b58b 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -81,10 +81,10 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 			  unsigned long len, unsigned long long highmem)
 {
 	unsigned long reserve = reserve_end - start;
-	long map_size = len - reserve;
+	unsigned long map_size = len - reserve;
 	int err;
 
-	if(map_size <= 0) {
+	if (len <= reserve) {
 		os_warn("Too few physical memory! Needed=%lu, given=%lu\n",
 			reserve, len);
 		exit(1);
@@ -95,7 +95,7 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 	err = os_map_memory((void *) reserve_end, physmem_fd, reserve,
 			    map_size, 1, 1, 1);
 	if (err < 0) {
-		os_warn("setup_physmem - mapping %ld bytes of memory at 0x%p "
+		os_warn("setup_physmem - mapping %lu bytes of memory at 0x%p "
 			"failed - errno = %d\n", map_size,
 			(void *) reserve_end, err);
 		exit(1);