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 43a3d9b ("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 torvalds#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: 43a3d9b ("i40evf: Allow PF driver to configure RSS")
Signed-off-by: Kohei Enju <[email protected]>

Author: hyperenju

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);