6.16-stable review patch. If anyone has any objections, please let me know.
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From: Duoming Zhou duoming@zju.edu.cn
[ Upstream commit f8b4687151021db61841af983f1cb7be6915d4ef ]
The original code relies on cancel_delayed_work() in otx2_ptp_destroy(), which does not ensure that the delayed work item synctstamp_work has fully completed if it was already running. This leads to use-after-free scenarios where otx2_ptp is deallocated by otx2_ptp_destroy(), while synctstamp_work remains active and attempts to dereference otx2_ptp in otx2_sync_tstamp(). Furthermore, the synctstamp_work is cyclic, the likelihood of triggering the bug is nonnegligible.
A typical race condition is illustrated below:
CPU 0 (cleanup) | CPU 1 (delayed work callback) otx2_remove() | otx2_ptp_destroy() | otx2_sync_tstamp() cancel_delayed_work() | kfree(ptp) | | ptp = container_of(...); //UAF | ptp-> //UAF
This is confirmed by a KASAN report:
BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x7d7/0x8c0 Write of size 8 at addr ffff88800aa09a18 by task bash/136 ... Call Trace: <IRQ> dump_stack_lvl+0x55/0x70 print_report+0xcf/0x610 ? __run_timer_base.part.0+0x7d7/0x8c0 kasan_report+0xb8/0xf0 ? __run_timer_base.part.0+0x7d7/0x8c0 __run_timer_base.part.0+0x7d7/0x8c0 ? __pfx___run_timer_base.part.0+0x10/0x10 ? __pfx_read_tsc+0x10/0x10 ? ktime_get+0x60/0x140 ? lapic_next_event+0x11/0x20 ? clockevents_program_event+0x1d4/0x2a0 run_timer_softirq+0xd1/0x190 handle_softirqs+0x16a/0x550 irq_exit_rcu+0xaf/0xe0 sysvec_apic_timer_interrupt+0x70/0x80 </IRQ> ... Allocated by task 1: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 otx2_ptp_init+0xb1/0x860 otx2_probe+0x4eb/0xc30 local_pci_probe+0xdc/0x190 pci_device_probe+0x2fe/0x470 really_probe+0x1ca/0x5c0 __driver_probe_device+0x248/0x310 driver_probe_device+0x44/0x120 __driver_attach+0xd2/0x310 bus_for_each_dev+0xed/0x170 bus_add_driver+0x208/0x500 driver_register+0x132/0x460 do_one_initcall+0x89/0x300 kernel_init_freeable+0x40d/0x720 kernel_init+0x1a/0x150 ret_from_fork+0x10c/0x1a0 ret_from_fork_asm+0x1a/0x30
Freed by task 136: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3a/0x60 __kasan_slab_free+0x3f/0x50 kfree+0x137/0x370 otx2_ptp_destroy+0x38/0x80 otx2_remove+0x10d/0x4c0 pci_device_remove+0xa6/0x1d0 device_release_driver_internal+0xf8/0x210 pci_stop_bus_device+0x105/0x150 pci_stop_and_remove_bus_device_locked+0x15/0x30 remove_store+0xcc/0xe0 kernfs_fop_write_iter+0x2c3/0x440 vfs_write+0x871/0xd70 ksys_write+0xee/0x1c0 do_syscall_64+0xac/0x280 entry_SYSCALL_64_after_hwframe+0x77/0x7f ...
Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure that the delayed work item is properly canceled before the otx2_ptp is deallocated.
This bug was initially identified through static analysis. To reproduce and test it, I simulated the OcteonTX2 PCI device in QEMU and introduced artificial delays within the otx2_sync_tstamp() function to increase the likelihood of triggering the bug.
Fixes: 2958d17a8984 ("octeontx2-pf: Add support for ptp 1-step mode on CN10K silicon") Signed-off-by: Duoming Zhou duoming@zju.edu.cn Reviewed-by: Vadim Fedorenko vadim.fedorenko@linux.dev Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/marvell/octeontx2/nic/otx2_ptp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_ptp.c +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_ptp.c @@ -491,7 +491,7 @@ void otx2_ptp_destroy(struct otx2_nic *p if (!ptp) return;
- cancel_delayed_work(&pfvf->ptp->synctstamp_work); + cancel_delayed_work_sync(&pfvf->ptp->synctstamp_work);
ptp_clock_unregister(ptp->ptp_clock); kfree(ptp);