published May 1, 2025
In the Linux kernel, the following vulnerability has been resolved:
misc/vmw_vmci: fix an infoleak in vmci_host_do_receive_datagram()
`struct vmci_event_qp` allocated by qp_notify_peer() contains padding,
which may carry uninitialized data to the userspace, as observed by
KMSAN:
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user ./include/linux/instrumented.h:121
instrument_copy_to_user ./include/linux/instrumented.h:121
_copy_to_user+0x5f/0xb0 lib/usercopy.c:33
copy_to_user ./include/linux/uaccess.h:169
vmci_host_do_receive_datagram drivers/misc/vmw_vmci/vmci_host.c:431
vmci_host_unlocked_ioctl+0x33d/0x43d0 drivers/misc/vmw_vmci/vmci_host.c:925
vfs_ioctl fs/ioctl.c:51
...
Uninit was stored to memory at:
kmemdup+0x74/0xb0 mm/util.c:131
dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:271
vmci_datagram_dispatch+0x4f8/0xfc0 drivers/misc/vmw_vmci/vmci_datagram.c:339
qp_notify_peer+0x19a/0x290 drivers/misc/vmw_vmci/vmci_queue_pair.c:1479
qp_broker_attach drivers/misc/vmw_vmci/vmci_queue_pair.c:1662
qp_broker_alloc+0x2977/0x2f30 drivers/misc/vmw_vmci/vmci_queue_pair.c:1750
vmci_qp_broker_alloc+0x96/0xd0 drivers/misc/vmw_vmci/vmci_queue_pair.c:1940
vmci_host_do_alloc_queuepair drivers/misc/vmw_vmci/vmci_host.c:488
vmci_host_unlocked_ioctl+0x24fd/0x43d0 drivers/misc/vmw_vmci/vmci_host.c:927
...
Local variable ev created at:
qp_notify_peer+0x54/0x290 drivers/misc/vmw_vmci/vmci_queue_pair.c:1456
qp_broker_attach drivers/misc/vmw_vmci/vmci_queue_pair.c:1662
qp_broker_alloc+0x2977/0x2f30 drivers/misc/vmw_vmci/vmci_queue_pair.c:1750
Bytes 28-31 of 48 are uninitialized
Memory access of size 48 starts at ffff888035155e00
Data copied to user address 0000000020000100
Use memset() to prevent the infoleaks.
Also speculatively fix qp_notify_peer_local(), which may suffer from the
same problem.