From bc35a6e445b59bd2fb0731a6e512b7271be85444 Mon Sep 17 00:00:00 2001
From: Augustin Cavalier <waddlesplash@gmail.com>
Date: Tue, 28 Feb 2023 19:08:41 -0500
Subject: [PATCH] kernel/vm: Prohibit offset from being < 0 in mmap.

POSIX seems to be silent about whether this is permitted,
but at least FreeBSD explicitly does not allow it.

Fixes #16936.

Change-Id: If6b23410ae88245e706df77d276234f4775654f9
---
 src/system/kernel/vm/vm.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/system/kernel/vm/vm.cpp b/src/system/kernel/vm/vm.cpp
index d318cdf078..88dc45ef28 100644
--- a/src/system/kernel/vm/vm.cpp
+++ b/src/system/kernel/vm/vm.cpp
@@ -941,6 +941,8 @@ map_backing_store(VMAddressSpace* addressSpace, VMCache* cache, off_t offset,
 #endif
 		return B_BAD_VALUE;
 	}
+	if (offset < 0)
+		return B_BAD_VALUE;
 
 	uint32 allocationFlags = HEAP_DONT_WAIT_FOR_MEMORY
 		| HEAP_DONT_LOCK_KERNEL_SPACE;