> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Kohei Enju
> Sent: Saturday, October 25, 2025 6:59 PM
> To: [email protected]; [email protected]
> Cc: Nguyen, Anthony L <[email protected]>; Kitszel,
> Przemyslaw <[email protected]>; Andrew Lunn
> <[email protected]>; David S. Miller <[email protected]>; Eric
> Dumazet <[email protected]>; Jakub Kicinski <[email protected]>; Paolo
> Abeni <[email protected]>; Mitch Williams
> <[email protected]>; [email protected]; Kohei Enju
> <[email protected]>
> Subject: [Intel-wired-lan] [PATCH iwl-net v1] iavf: fix off-by-one
> issues in iavf_config_rss_reg()
>
> There are off-by-one bugs when configuring RSS hash key and lookup
> table, causing out-of-bounds reads to memory [1] and out-of-bounds
> writes to device registers.
>
> Before commit 43a3d9ba34c9 ("i40evf: Allow PF driver to configure
> RSS"), the loop upper bounds were:
> i <= I40E_VFQF_{HKEY,HLUT}_MAX_INDEX which is safe since the value
> is the last valid index.
>
> That commit changed the bounds to:
> i <= adapter->rss_{key,lut}_size / 4 where `rss_{key,lut}_size /
> 4` is the number of dwords, so the last valid index is
> `(rss_{key,lut}_size / 4) - 1`. Therefore, using `<=` accesses one
> element past the end.
>
> Fix the issues by using `<` instead of `<=`, ensuring we do not exceed
> the bounds.
>
> [1] KASAN splat about rss_key_size off-by-one
> BUG: KASAN: slab-out-of-bounds in iavf_config_rss+0x619/0x800
> Read of size 4 at addr ffff888102c50134 by task kworker/u8:6/63
>
> CPU: 0 UID: 0 PID: 63 Comm: kworker/u8:6 Not tainted 6.18.0-rc2-
> enjuk-tnguy-00378-g3005f5b77652-dirty #156 PREEMPT(voluntary)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-
> debian-1.16.3-2 04/01/2014
> Workqueue: iavf iavf_watchdog_task
> Call Trace:
> <TASK>
> dump_stack_lvl+0x6f/0xb0
> print_report+0x170/0x4f3
> kasan_report+0xe1/0x1a0
> iavf_config_rss+0x619/0x800
> iavf_watchdog_task+0x2be7/0x3230
> process_one_work+0x7fd/0x1420
> worker_thread+0x4d1/0xd40
> kthread+0x344/0x660
> ret_from_fork+0x249/0x320
> ret_from_fork_asm+0x1a/0x30
> </TASK>
>
> Allocated by task 63:
> kasan_save_stack+0x30/0x50
> kasan_save_track+0x14/0x30
> __kasan_kmalloc+0x7f/0x90
> __kmalloc_noprof+0x246/0x6f0
> iavf_watchdog_task+0x28fc/0x3230
> process_one_work+0x7fd/0x1420
> worker_thread+0x4d1/0xd40
> kthread+0x344/0x660
> ret_from_fork+0x249/0x320
> ret_from_fork_asm+0x1a/0x30
>
> The buggy address belongs to the object at ffff888102c50100
> which belongs to the cache kmalloc-64 of size 64
> The buggy address is located 0 bytes to the right of
> allocated 52-byte region [ffff888102c50100, ffff888102c50134)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
> pfn:0x102c50
> flags: 0x200000000000000(node=0|zone=2)
> page_type: f5(slab)
> raw: 0200000000000000 ffff8881000418c0 dead000000000122
> 0000000000000000
> raw: 0000000000000000 0000000080200020 00000000f5000000
> 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff888102c50000: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
> ffff888102c50080: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
> >ffff888102c50100: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc
> ^
> ffff888102c50180: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> ffff888102c50200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>
> Fixes: 43a3d9ba34c9 ("i40evf: Allow PF driver to configure RSS")
> Signed-off-by: Kohei Enju <[email protected]>
> ---
> drivers/net/ethernet/intel/iavf/iavf_main.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c
> b/drivers/net/ethernet/intel/iavf/iavf_main.c
> index c2fbe443ef85..4b0fc8f354bc 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
> @@ -1726,11 +1726,11 @@ static int iavf_config_rss_reg(struct
> iavf_adapter *adapter)
> u16 i;
>
> dw = (u32 *)adapter->rss_key;
> - for (i = 0; i <= adapter->rss_key_size / 4; i++)
> + for (i = 0; i < adapter->rss_key_size / 4; i++)
> wr32(hw, IAVF_VFQF_HKEY(i), dw[i]);
>
> dw = (u32 *)adapter->rss_lut;
> - for (i = 0; i <= adapter->rss_lut_size / 4; i++)
> + for (i = 0; i < adapter->rss_lut_size / 4; i++)
> wr32(hw, IAVF_VFQF_HLUT(i), dw[i]);
>
> iavf_flush(hw);
> --
> 2.51.0
Reviewed-by: Aleksandr Loktionov <[email protected]>
