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[mickledore,17/30] scripts/runqemu: allocate unfsd ports in a way that doesn't race or clash with unrelated processes

Message ID 3dccfba830bfbe89554a5e3ed5c3517d13545d35.1688092011.git.steve@sakoman.com
State New
Headers show
Series [mickledore,01/30] tiff: Security fix for CVE-2023-25434 and CVE-2023-26965 | expand

Commit Message

Steve Sakoman June 30, 2023, 2:28 a.m. UTC 
From: Alexander Kanavin <alex.kanavin@gmail.com>

There is already a neat check_free_port() function for finding an available port
atomically, so use that and make two additional tweaks:

- no need to allocate two separate ports; per unfsd documentation they can be the same

- move lockfile release until after unfsd has been shut down and the port(s) used has been freed

[YOCTO #15077]

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit dee96e82fb04ea99ecd6c25513c7bd368df3bd37)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
---
 scripts/runqemu | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)
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Patch

diff --git a/scripts/runqemu b/scripts/runqemu
index 50224f2784..ef24ddc6b2 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -1011,17 +1011,14 @@  to your build configuration.
             else:
                 self.nfs_server = '192.168.7.@GATEWAY@'
 
-        # Figure out a new nfs_instance to allow multiple qemus running.
-        ps = subprocess.check_output(("ps", "auxww")).decode('utf-8')
-        pattern = '/bin/unfsd .* -i .*\.pid -e .*/exports([0-9]+) '
-        all_instances = re.findall(pattern, ps, re.M)
-        if all_instances:
-            all_instances.sort(key=int)
-            self.nfs_instance = int(all_instances.pop()) + 1
-
-        nfsd_port = 3049 + 2 * self.nfs_instance
-        mountd_port = 3048 + 2 * self.nfs_instance
+        nfsd_port = 3048 + self.nfs_instance
+        lockdir = "/tmp/qemu-port-locks"
+        self.make_lock_dir(lockdir)
+        while not self.check_free_port('localhost', nfsd_port, lockdir):
+            self.nfs_instance += 1
+            nfsd_port += 1
 
+        mountd_port = nfsd_port
         # Export vars for runqemu-export-rootfs
         export_dict = {
             'NFS_INSTANCE': self.nfs_instance,
@@ -1595,13 +1592,13 @@  to your build configuration.
             logger.debug('Running %s' % str(cmd))
             subprocess.check_call(cmd)
         self.release_taplock()
-        self.release_portlock()
 
         if self.nfs_running:
             logger.info("Shutting down the userspace NFS server...")
             cmd = ("runqemu-export-rootfs", "stop", self.rootfs)
             logger.debug('Running %s' % str(cmd))
             subprocess.check_call(cmd)
+        self.release_portlock()
 
         if self.saved_stty:
             subprocess.check_call(("stty", self.saved_stty))