[PATCH net v4 1/2] net: stmmac: replace memcpy with ethtool_puts in ethtool

[Konrad Leszczynski <konrad.leszczynski@intel.com>]

Fix kernel exception by replacing memcpy with ethtool_puts when used with
safety feature strings in ethtool logic.

[  +0.000023] BUG: KASAN: global-out-of-bounds in stmmac_get_strings+0x17d/0x520 [stmmac]
[  +0.000115] Read of size 32 at addr ffffffffc0cfab20 by task ethtool/2571

[  +0.000005] Call Trace:
[  +0.000004]  <TASK>
[  +0.000003]  dump_stack_lvl+0x6c/0x90
[  +0.000016]  print_report+0xce/0x610
[  +0.000011]  ? stmmac_get_strings+0x17d/0x520 [stmmac]
[  +0.000108]  ? kasan_addr_to_slab+0xd/0xa0
[  +0.000008]  ? stmmac_get_strings+0x17d/0x520 [stmmac]
[  +0.000101]  kasan_report+0xd4/0x110
[  +0.000010]  ? stmmac_get_strings+0x17d/0x520 [stmmac]
[  +0.000102]  kasan_check_range+0x3a/0x1c0
[  +0.000010]  __asan_memcpy+0x24/0x70
[  +0.000008]  stmmac_get_strings+0x17d/0x520 [stmmac]

Reviewed-by: Sebastian Basierski <sebastian.basierski@intel.com>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Signed-off-by: Konrad Leszczynski <konrad.leszczynski@intel.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
index 77758a7299b4..d5a2b7e9b2a9 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
@@ -752,7 +752,7 @@ static void stmmac_get_strings(struct net_device *dev, u32 stringset, u8 *data)
 				if (!stmmac_safety_feat_dump(priv,
 							&priv->sstats, i,
 							NULL, &desc)) {
-					memcpy(p, desc, ETH_GSTRING_LEN);
+					ethtool_puts(&p, desc);
 					p += ETH_GSTRING_LEN;
 				}
 			}
-- 
2.34.1