From 811429bfd4a46f33c7788580f72038b0c3c1c2b1 Mon Sep 17 00:00:00 2001
From: Jan Beich <jbeich@FreeBSD.org>
Date: Mon, 10 Jun 2024 20:31:03 +0000
Subject: [PATCH] wayland: consistently check mmap error after 6967a3145044
 (#6402)

mmap() returns MAP_FAILED on error, not nullptr.
---
 src/protocols/LinuxDMABUF.cpp | 2 +-
 src/protocols/core/Shm.cpp    | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/protocols/LinuxDMABUF.cpp b/src/protocols/LinuxDMABUF.cpp
index f7911f6e..cf8f8730 100644
--- a/src/protocols/LinuxDMABUF.cpp
+++ b/src/protocols/LinuxDMABUF.cpp
@@ -38,7 +38,7 @@ CCompiledDMABUFFeedback::CCompiledDMABUFFeedback(dev_t device, std::vector<SDMAB
 
     auto arr = (SDMABUFFeedbackTableEntry*)mmap(nullptr, tableLen, PROT_READ | PROT_WRITE, MAP_SHARED, fds[0], 0);
 
-    if (!arr) {
+    if (arr == MAP_FAILED) {
         LOGM(ERR, "mmap failed");
         close(fds[0]);
         close(fds[1]);
diff --git a/src/protocols/core/Shm.cpp b/src/protocols/core/Shm.cpp
index ce7d3a61..4088949f 100644
--- a/src/protocols/core/Shm.cpp
+++ b/src/protocols/core/Shm.cpp
@@ -97,7 +97,7 @@ void CSHMPool::resize(size_t size_) {
     size = size_;
     data = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 
-    if (!data)
+    if (data == MAP_FAILED)
         LOGM(ERR, "Couldn't mmap {} bytes from fd {} of shm client", size, fd);
 }
 
@@ -146,7 +146,7 @@ CWLSHMPoolResource::CWLSHMPoolResource(SP<CWlShmPool> resource_, int fd_, size_t
         RESOURCE->resource->buffer = RESOURCE;
     });
 
-    if (!pool->data)
+    if (pool->data == MAP_FAILED)
         resource->error(WL_SHM_ERROR_INVALID_FD, "Couldn't mmap from fd");
 }