Jeff, Dave,
This is a pretty bad issue as one can crash a kernel quite easily by
forcing interrupt affinity changes.
We now have three versions of this patch, with exactly the same code
changes. I posted mine as I independently found this issue last week
and didn't notice Juergen patch which was posted two days earlier.
I didn't notice the other patch in the pull request from Jeff either, I
just checked his tree and it wasn't there until yesterday. Frankly
speaking, I think this was quite vaguely worded and hidden in the cover
letter, and queued up for net-next, while it should really go to net as
it fixes a panic in mainline.
FWIW, I don't care too much about which version ends up applied, even
though I'd prefer one which a commit message which clearly describes
the issue with its implications and reports the right Fixed: tag. Both
my patch and Juergen's v2, posted later, are fine by me (I still think
mine is a bit clearer).
--
Stefano
On Tue, 15 Aug 2017 12:30:14 +0200
Stefano Brivio <sbri...@redhat.com> wrote:
> The cpumask used in i40e{,vf}_irq_affinity_notify() is allocated
> by irq_affinity_notify() with alloc_cpumask_var(), which doesn't
> allocate NR_CPUS bits, but only nr_cpumask_bits bits. If we just
> dereference it, we'll read way more than what is allocated, e.g.
> 1024 bytes vs. 8 bytes allocated on x86_64 machine with 24 CPUs.
>
> Use cpumask_copy() instead. A comprehensive explanation is given
> in the comments about cpumask_var_t, in include/linux/cpumask.h.
>
> KASAN reports:
> [ 25.242312] BUG: KASAN: slab-out-of-bounds in
> i40e_irq_affinity_notify+0x30/0x50 [i40e] at addr ffff880462eea960
> [ 25.242315] Read of size 1024 by task kworker/2:1/170
> [ 25.242322] CPU: 2 PID: 170 Comm: kworker/2:1 Not tainted
> 4.11.0-22.el7a.x86_64 #1
> [ 25.242325] Hardware name: HP ProLiant DL380 Gen9, BIOS P89 05/06/2015
> [ 25.242336] Workqueue: events irq_affinity_notify
> [ 25.242340] Call Trace:
> [ 25.242350] dump_stack+0x63/0x8d
> [ 25.242358] kasan_object_err+0x21/0x70
> [ 25.242364] kasan_report+0x288/0x540
> [ 25.242397] ? i40e_irq_affinity_notify+0x30/0x50 [i40e]
> [ 25.242403] check_memory_region+0x13c/0x1a0
> [ 25.242408] __asan_loadN+0xf/0x20
> [ 25.242440] i40e_irq_affinity_notify+0x30/0x50 [i40e]
> [ 25.242446] irq_affinity_notify+0x1b4/0x230
> [ 25.242452] ? irq_set_affinity_notifier+0x130/0x130
> [ 25.242457] ? kasan_slab_free+0x89/0xc0
> [ 25.242466] process_one_work+0x32f/0x6f0
> [ 25.242472] worker_thread+0x89/0x770
> [ 25.242481] ? pci_mmcfg_check_reserved+0xc0/0xc0
> [ 25.242488] kthread+0x18c/0x1e0
> [ 25.242493] ? process_one_work+0x6f0/0x6f0
> [ 25.242499] ? kthread_create_on_node+0xc0/0xc0
> [ 25.242506] ret_from_fork+0x2c/0x40
> [ 25.242511] Object at ffff880462eea960, in cache kmalloc-8 size: 8
> [ 25.242513] Allocated:
> [ 25.242514] PID = 170
> [ 25.242522] save_stack_trace+0x1b/0x20
> [ 25.242529] save_stack+0x46/0xd0
> [ 25.242533] kasan_kmalloc+0xad/0xe0
> [ 25.242537] __kmalloc_node+0x12c/0x2b0
> [ 25.242542] alloc_cpumask_var_node+0x3c/0x60
> [ 25.242546] alloc_cpumask_var+0xe/0x10
> [ 25.242550] irq_affinity_notify+0x94/0x230
> [ 25.242555] process_one_work+0x32f/0x6f0
> [ 25.242559] worker_thread+0x89/0x770
> [ 25.242564] kthread+0x18c/0x1e0
> [ 25.242568] ret_from_fork+0x2c/0x40
> [ 25.242569] Freed:
> [ 25.242570] PID = 0
> [ 25.242572] (stack is not available)
> [ 25.242573] Memory state around the buggy address:
> [ 25.242578] ffff880462eea800: fc fc 00 fc fc 00 fc fc 00 fc fc 00 fc fc
> fb fc
> [ 25.242582] ffff880462eea880: fc fb fc fc fb fc fc 00 fc fc 00 fc fc 00
> fc fc
> [ 25.242586] >ffff880462eea900: 00 fc fc 00 fc fc 00 fc fc fb fc fc 00 fc
> fc fc
> [ 25.242588] ^
> [ 25.242592] ffff880462eea980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> fc fc
> [ 25.242596] ffff880462eeaa00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> fc fc
> [ 25.242597]
> ==================================================================
>
> Fixes: 96db776a3682 ("i40e/i40evf: fix interrupt affinity bug")
> Signed-off-by: Stefano Brivio <sbri...@redhat.com>
> ---
> This should be considered for -stable, back to 4.10.
>
> drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +-
> drivers/net/ethernet/intel/i40evf/i40evf_main.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 2db93d3f6d23..c0e42d162c7c 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -3495,7 +3495,7 @@ static void i40e_irq_affinity_notify(struct
> irq_affinity_notify *notify,
> struct i40e_q_vector *q_vector =
> container_of(notify, struct i40e_q_vector, affinity_notify);
>
> - q_vector->affinity_mask = *mask;
> + cpumask_copy(&q_vector->affinity_mask, mask);
> }
>
> /**
> diff --git a/drivers/net/ethernet/intel/i40evf/i40evf_main.c
> b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
> index 7c213a347909..a4b60367ecce 100644
> --- a/drivers/net/ethernet/intel/i40evf/i40evf_main.c
> +++ b/drivers/net/ethernet/intel/i40evf/i40evf_main.c
> @@ -520,7 +520,7 @@ static void i40evf_irq_affinity_notify(struct
> irq_affinity_notify *notify,
> struct i40e_q_vector *q_vector =
> container_of(notify, struct i40e_q_vector, affinity_notify);
>
> - q_vector->affinity_mask = *mask;
> + cpumask_copy(&q_vector->affinity_mask, mask);
> }
>
> /**
