When IPv6 module gets initialized, but it's hitting an error in inet6_init()
where it then needs to undo all the prior initialization work, it also might
do a call to ndisc_cleanup() which then calls neigh_table_clear(). In there
is a missing timer cancellation of the table's managed_work item.
The kernel test robot explicitly triggered this error path and caused a UAF
crash similar to the below:
[...]
[ 28.833183][ C0] BUG: unable to handle page fault for address: f7a43288
[ 28.833973][ C0] #PF: supervisor write access in kernel mode
[ 28.834660][ C0] #PF: error_code(0x0002) - not-present page
[ 28.835319][ C0] *pde = 06b2c067 *pte = 00000000
[ 28.835853][ C0] Oops: 0002 [#1] PREEMPT
[ 28.836367][ C0] CPU: 0 PID: 303 Comm: sed Not tainted 5.16.0-rc1-00233-g83ff5faa0d3b #7
[ 28.837293][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1 04/01/2014
[ 28.838338][ C0] EIP: __run_timers.constprop.0+0x82/0x440
[...]
[ 28.845607][ C0] Call Trace:
[ 28.845942][ C0] <SOFTIRQ>
[ 28.846333][ C0] ? check_preemption_disabled.isra.0+0x2a/0x80
[ 28.846975][ C0] ? __this_cpu_preempt_check+0x8/0xa
[ 28.847570][ C0] run_timer_softirq+0xd/0x40
[ 28.848050][ C0] __do_softirq+0xf5/0x576
[ 28.848547][ C0] ? __softirqentry_text_start+0x10/0x10
[ 28.849127][ C0] do_softirq_own_stack+0x2b/0x40
[ 28.849749][ C0] </SOFTIRQ>
[ 28.850087][ C0] irq_exit_rcu+0x7d/0xc0
[ 28.850587][ C0] common_interrupt+0x2a/0x40
[ 28.851068][ C0] asm_common_interrupt+0x119/0x120
[...]
Note that IPv6 module cannot be unloaded as per 8ce4406103 ("ipv6: do not
allow ipv6 module to be removed") hence this can only be seen during module
initialization error. Tested with kernel test robot's reproducer.
Fixes: 7482e3841d ("net, neigh: Add NTF_MANAGED flag for managed neighbor entries")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Li Zhijian <zhijianx.li@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
4177d5b017