bnxt_en: Fix NULL pointer crash in bnxt_ptp_enable during error cleanup

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

bnxt_en: Fix NULL pointer crash in bnxt_ptp_enable during error cleanup

When bnxt_init_one() fails during initialization (e.g.,

bnxt_init_int_mode returns -ENODEV), the error path calls

bnxt_free_hwrm_resources() which destroys the DMA pool and sets

bp->hwrm_dma_pool to NULL. Subsequently, bnxt_ptp_clear() is called,

which invokes ptp_clock_unregister().

Since commit a60fc3294a37 ("ptp: rework ptp_clock_unregister() to

disable events"), ptp_clock_unregister() now calls

ptp_disable_all_events(), which in turn invokes the driver's .enable()

callback (bnxt_ptp_enable()) to disable PTP events before completing the

unregistration.

bnxt_ptp_enable() attempts to send HWRM commands via bnxt_ptp_cfg_pin()

and bnxt_ptp_cfg_event(), both of which call hwrm_req_init(). This

function tries to allocate from bp->hwrm_dma_pool, causing a NULL

pointer dereference:

bnxt_en 0000:01:00.0 (unnamed net_device) (uninitialized): bnxt_init_int_mode err: ffffffed

KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]

Call Trace:

__hwrm_req_init (drivers/net/ethernet/broadcom/bnxt/bnxt_hwrm.c:72)

bnxt_ptp_enable (drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c:323 drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c:517)

ptp_disable_all_events (drivers/ptp/ptp_chardev.c:66)

ptp_clock_unregister (drivers/ptp/ptp_clock.c:518)

bnxt_ptp_clear (drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c:1134)

bnxt_init_one (drivers/net/ethernet/broadcom/bnxt/bnxt.c:16889)

Lines are against commit f8f9c1f4d0c7 ("Linux 6.19-rc3")

Fix this by clearing and unregistering ptp (bnxt_ptp_clear()) before

freeing HWRM resources.