can: bcm: fix stale rx/tx ops after device removal

Overview

In the Linux kernel, the following vulnerability has been resolved:

can: bcm: fix stale rx/tx ops after device removal

RX: an RX_SETUP update(!) for an existing op skipped can_rx_register() unconditionally, even when a concurrent NETDEV_UNREGISTER had already torn down its registration (op->rx_reg_dev == NULL). This silently did not re-enable frame delivery for that updated filter. bcm_rx_setup() now re-registers in that case, while leaving rx_ops with ifindex = 0 (all CAN devices) which never carry a tracked rx_reg_dev registered as-is.

TX: bcm_notify() only handled bo->rx_ops on NETDEV_UNREGISTER, leaving tx_ops with an active cyclic transmission re-arming its hrtimer indefinitely to execute bcm_tx_timeout_handler(). Cancelling the hrtimer prevents the runaway timer and any injection into a later reused ifindex, since nothing else calls bcm_can_tx() for the op until an explicit TX_SETUP update re-arms it.

Unlike bcm_rx_unreg(), which clears the tracked rx_reg_dev for rx_ops, the ifindex is intentionally left unchanged for tx_ops. bcm_tx_setup() always rejects ifindex 0, so clearing it would strand the op: neither a later TX_SETUP (bcm_find_op()) nor TX_DELETE (bcm_delete_tx_op()) could ever find it again, since both require an exact ifindex match.

Affected

• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < d30a36066ed3abefb72ae18901f71841ba18b350
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < ca829677ffa2de5d79e06366e19ac1e4f5cc78dd
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < 9517d8fb0b191398d35b9b7f8c719c1cc7761cb1
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < 60d8a7942f4ed2d975207aaeba1adb576707e53d
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < f749e4564952d60e96930c09f2be99955d07c22e
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < 6be3e1fedf03eab36a2c09d755d1171287b2014b
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < b31d0933509c5a35c0be5736a2ce8df0d1bf112c
• Linux >= ffd980f976e7fd666c2e61bf8ab35107efd11828 < 3b762c0d950383ab7a002686c9136b9aa55d2d70
• Linux 2.6.25

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.