From 400f5c14e6d02de1e6f928ef542679cb591a0a1c Mon Sep 17 00:00:00 2001
From: Olivier Valentin <ovalenti@redhat.com>
Date: Mon, 9 Dec 2024 16:02:52 +0100
Subject: [PATCH] Skip parsing of zombie processes.

---
 collector/lib/ProcfsScraper.cpp | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/collector/lib/ProcfsScraper.cpp b/collector/lib/ProcfsScraper.cpp
index a06779c95e..2348f8d92c 100644
--- a/collector/lib/ProcfsScraper.cpp
+++ b/collector/lib/ProcfsScraper.cpp
@@ -144,6 +144,26 @@ bool GetSocketINodes(int dirfd, uint64_t pid, UnorderedSet<SocketInfo>* sock_ino
   return true;
 }
 
+// IsZombieProcess fetches the current state of the process pointed to by dirfd, and
+// - returns true, if the process state is 'Z'
+// - returns false otherwise
+bool IsZombieProcess(int dirfd) {
+  FileHandle stat_file(FDHandle(openat(dirfd, "stat", O_RDONLY)), "r");
+  if (!stat_file.valid()) {
+    return false;
+  }
+
+  char linebuf[512];
+
+  if (fgets(linebuf, sizeof(linebuf), stat_file.get()) == nullptr) {
+    return false;
+  }
+
+  auto state = ExtractProcessState(linebuf);
+
+  return state && *state == 'Z';
+}
+
 // GetContainerID retrieves the container ID of the process represented by dirfd. The container ID is extracted from
 // the cgroup.
 std::optional<std::string> GetContainerID(int dirfd) {
@@ -492,6 +512,10 @@ bool ReadContainerConnections(const char* proc_path, std::shared_ptr<ProcessStor
       continue;
     }
 
+    if (IsZombieProcess(dirfd)) {
+      continue;
+    }
+
     auto container_id = GetContainerID(dirfd);
     if (!container_id) {
       continue;
@@ -499,7 +523,6 @@ bool ReadContainerConnections(const char* proc_path, std::shared_ptr<ProcessStor
 
     uint64_t netns_inode;
     if (!GetNetworkNamespace(dirfd, &netns_inode)) {
-      // TODO ROX-13962: Improve logging to indicate when a process is defunct.
       COUNTER_INC(CollectorStats::procfs_could_not_get_network_namespace);
       CLOG_THROTTLED(ERROR, std::chrono::seconds(10)) << "Could not determine network namespace: " << StrError();
       continue;