Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
ice: fix race condition in TX timestamp ring cleanup
Fix a race condition between ice_free_tx_tstamp_ring() and ice_tx_map() that can cause a NULL pointer dereference.
ice_free_tx_tstamp_ring currently clears the ICE_TX_FLAGS_TXTIME flag after NULLing the tstamp_ring. This could allow a concurrent ice_tx_map call on another CPU to dereference the tstamp_ring, which could lead to a NULL pointer dereference.
| CPU A:ice_free_tx_tstamp_ring() | CPU B:ice_tx_map() |
|---|---|
| tx_ring->tstamp_ring = NULL | |
| ice_is_txtime_cfg() -> true | |
| tstamp_ring = tx_ring->tstamp_ring | |
| tstamp_ring->count // NULL deref! | |
| flags &= ~ICE_TX_FLAGS_TXTIME |
Fix by:
- Reordering ice_free_tx_tstamp_ring() to clear the flag before NULLing the pointer, with smp_wmb() to ensure proper ordering.
- Adding smp_rmb() in ice_tx_map() after the flag check to order the flag read before the pointer read, using READ_ONCE() for the pointer, and adding a NULL check as a safety net.
- Converting tx_ring->flags from u8 to DECLARE_BITMAP() and using atomic bitops (set_bit(), clear_bit(), test_bit()) for all flag operations throughout the driver:
- ICE_TX_RING_FLAGS_XDP
- ICE_TX_RING_FLAGS_VLAN_L2TAG1
- ICE_TX_RING_FLAGS_VLAN_L2TAG2
- ICE_TX_RING_FLAGS_TXTIME
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 5.14.0 (+1 more)