relid2channel() assumes vmbus channel array to be allocated when called.
However, in cases such as kdump/kexec, not all relids will be reset by the host.
When the second kernel boots and if the guest receives a vmbus interrupt during
vmbus driver initialization before vmbus_connect() is called, before it finishes,
or if it fails, the vmbus interrupt service routine is called which in turn calls
relid2channel() and can cause a null pointer dereference.
So Make relid2channel() check if vmbus channels is allocated first, and if not
print a warning and return NULL to the caller.
Fixes: 8b6a877c060e ("Drivers: hv: vmbus: Replace the per-CPU channel lists with a global array of channels")
Signed-off-by: Mohammed Gamal <mgamal@xxxxxxxxxx>
---
Changes from v1:
* Corrected and detailed description in commit message
* Added detailed warning message
---
drivers/hv/connection.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 9dc27e5d367a..82876e84f719 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -409,6 +409,10 @@ void vmbus_disconnect(void)
*/
struct vmbus_channel *relid2channel(u32 relid)
{
+ if (vmbus_connection.channels == NULL) {
+ WARN(1, "Requested relid=%u, but channel mapping not allocated!\n", relid);
+ return NULL;
+ }
if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
return NULL;
return READ_ONCE(vmbus_connection.channels[relid]);
--
2.38.1
