Merge #32 `Fix for systems with page size larger than 4k`

epel8
Tom Callaway 2 years ago
commit fc64fd023d

@ -0,0 +1,86 @@
From 96ee2a8e20bb7a7c4fb19e27dc31ff5c6a472849 Mon Sep 17 00:00:00 2001
From: Ryan Gonzalez <rymg19@gmail.com>
Date: Mon, 06 Mar 2023 20:22:25 -0600
Subject: [PATCH] AddressTrackerLinux: Increase the message buffer size
On non-4k-page systems, the message sizes may be too large to fit into
the buffer, resulting in MSG_TRUNC. Instead of using the fixed 4kb size,
follow the kernel documentation guidelines as to how large the buffer
should be.
Originally found by Asahi Lina:
https://vt.social/@lina/109976892758680822
Bug: None
Change-Id: I4790435190167a706fa7490ab57706db1f4a6120
---
diff --git a/net/base/address_tracker_linux.cc b/net/base/address_tracker_linux.cc
index 4976cae..f1a1fff 100644
--- a/net/base/address_tracker_linux.cc
+++ b/net/base/address_tracker_linux.cc
@@ -14,6 +14,7 @@
#include "base/files/scoped_file.h"
#include "base/functional/callback_helpers.h"
#include "base/logging.h"
+#include "base/memory/page_size.h"
#include "base/posix/eintr_wrapper.h"
#include "base/task/current_thread.h"
#include "base/threading/scoped_blocking_call.h"
@@ -323,8 +324,30 @@
*address_changed = false;
*link_changed = false;
*tunnel_changed = false;
- char buffer[4096];
bool first_loop = true;
+
+ // Varying sources have different opinions regarding the buffer size needed
+ // for netlink messages to avoid truncation:
+ // - The official documentation on netlink says messages are generally 8kb
+ // or the system page size, whichever is *larger*:
+ // https://www.kernel.org/doc/html/v6.2/userspace-api/netlink/intro.html#buffer-sizing
+ // - The kernel headers would imply that messages are generally the system
+ // page size or 8kb, whichever is *smaller*:
+ // https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/include/linux/netlink.h?h=v6.2.2#n226
+ // (libmnl follows this.)
+ // - The netlink(7) man page's example always uses a fixed size 8kb buffer:
+ // https://man7.org/linux/man-pages/man7/netlink.7.html
+ // Here, we follow the guidelines in the documentation, for two primary
+ // reasons:
+ // - Erring on the side of a larger size is the safer way to go to avoid
+ // MSG_TRUNC.
+ // - Since this is heap-allocated anyway, there's no risk to the stack by
+ // using the larger size.
+
+ constexpr size_t kMinNetlinkBufferSize = 8 * 1024;
+ std::vector<char> buffer(
+ std::max(base::GetPageSize(), kMinNetlinkBufferSize));
+
{
absl::optional<base::ScopedBlockingCall> blocking_call;
if (tracking_) {
@@ -334,9 +357,10 @@
}
for (;;) {
- int rv = HANDLE_EINTR(recv(netlink_fd_.get(), buffer, sizeof(buffer),
- // Block the first time through loop.
- first_loop ? 0 : MSG_DONTWAIT));
+ int rv =
+ HANDLE_EINTR(recv(netlink_fd_.get(), buffer.data(), buffer.size(),
+ // Block the first time through loop.
+ first_loop ? 0 : MSG_DONTWAIT));
first_loop = false;
if (rv == 0) {
LOG(ERROR) << "Unexpected shutdown of NETLINK socket.";
@@ -348,7 +372,8 @@
PLOG(ERROR) << "Failed to recv from netlink socket";
return;
}
- HandleMessage(buffer, rv, address_changed, link_changed, tunnel_changed);
+ HandleMessage(buffer.data(), rv, address_changed, link_changed,
+ tunnel_changed);
}
}
if (*link_changed || *address_changed)

@ -365,6 +365,8 @@ Patch122: chromium-109-gcc13.patch
# Patches by Stephan Hartmann, https://github.com/stha09/chromium-patches
Patch130: chromium-103-VirtualCursor-std-layout.patch
Patch146: chromium-110-LargerThan4k.patch
# VAAPI
# Upstream turned VAAPI on in Linux in 86
Patch202: chromium-104.0.5112.101-enable-hardware-accelerated-mjpeg.patch
@ -957,6 +959,8 @@ udev.
%patch130 -p1 -b .VirtualCursor-std-layout
%patch146 -p1 -b .LargerThan4k
%if %{use_qt}
%patch121 -p1 -b .enable-allowqt
%endif

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