[PATCH] serialize access pci_get_strings function with a mutex

[wangjian <wangjian161@xxxxxxxxxx>]

serialize access pci_get_strings function with a mutex.

nodedev-init thread:
nodeStateInitializeEnumerate ->
  udevEnumerateDevices->
    udevProcessDeviceListEntry ->
      udevAddOneDevice ->
        udevGetDeviceDetails->
          udevProcessPCI ->
            udevTranslatePCIIds ->
              pci_get_strings -> (libpciaccess)
                find_device_name ->
                  populate_vendor ->
                    d = realloc( vend->devices, (vend->num_devices + 1), * sizeof( struct pci_device_leaf ) );
                    vend->num_devices++;

udev-event thread:
udevEventHandleThread ->
  udevHandleOneDevice ->
    udevAddOneDevice->
      udevGetDeviceDetails->
        udevProcessPCI ->
          udevTranslatePCIIds ->
            pci_get_strings -> (libpciaccess)
              find_device_name ->
                populate_vendor ->
                  d = realloc( vend->devices, (vend->num_devices + 1), * sizeof( struct pci_device_leaf ) );
                  vend->num_devices++;

Since the functions provided by libpciaccess are not thread-safe,
when the udev-event and nodedev-init threads of libvirt call
the pci_get_strings function provided by libpaciaccess at the same time.
It will appear that for the same address, realloc a large space first,
and then realloc a small space, which triggers the 'invalid next size' of realloc,
leading to the thread core.

Signed-off-by: WangJian <wangjian161@xxxxxxxxxx>
---
 src/node_device/node_device_udev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 3f28858..cc752ba 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -331,6 +331,7 @@ udevGenerateDeviceName(struct udev_device *device,
     return 0;
 }

+static pthread_mutex_t g_pciaccess_mutex = PTHREAD_MUTEX_INITIALIZER;

 static int
 udevTranslatePCIIds(unsigned int vendor,
@@ -350,11 +351,13 @@ udevTranslatePCIIds(unsigned int vendor,
     m.match_data = 0;

     /* pci_get_strings returns void */
+    pthread_mutex_lock(&g_pciaccess_mutex);
     pci_get_strings(&m,
                     &device_name,
                     &vendor_name,
                     NULL,
                     NULL);
+    pthread_mutex_unlock(&g_pciaccess_mutex);

     *vendor_string = g_strdup(vendor_name);
     *product_string = g_strdup(device_name);
-- 
2.23.0