[PATCH net-next] qed: Fix copying 2 strings

[PATCH net-next] qed: Fix copying 2 strings

[Denis Bolotin]

The strscpy() was a recent fix (net: qed: use correct strncpy() size) to
prevent passing the length of the source buffer to strncpy() and guarantee
null termination.
It misses the goal of overwriting only the first 3 characters in
"???_BIG_RAM" and "???_RAM" while keeping the rest of the string.
Use strncpy() with the length of 3, without null termination.

Signed-off-by: Denis Bolotin <denis.bolotin@cavium.com>
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
---
 drivers/net/ethernet/qlogic/qed/qed_debug.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_debug.c b/drivers/net/ethernet/qlogic/qed/qed_debug.c
index b3211c7..39124b5 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_debug.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_debug.c
@@ -419,6 +419,7 @@ struct phy_defs {
 #define NUM_RSS_MEM_TYPES		5
 
 #define NUM_BIG_RAM_TYPES		3
+#define BIG_RAM_NAME_LEN		3
 
 #define NUM_PHY_TBUS_ADDRESSES		2048
 #define PHY_DUMP_SIZE_DWORDS		(NUM_PHY_TBUS_ADDRESSES / 2)
@@ -3650,8 +3651,8 @@ static u32 qed_grc_dump_big_ram(struct qed_hwfn *p_hwfn,
 		     BIT(big_ram->is_256b_bit_offset[dev_data->chip_id]) ? 256
 									 : 128;
 
-	strscpy(type_name, big_ram->instance_name, sizeof(type_name));
-	strscpy(mem_name, big_ram->instance_name, sizeof(mem_name));
+	strncpy(type_name, big_ram->instance_name, BIG_RAM_NAME_LEN);
+	strncpy(mem_name, big_ram->instance_name, BIG_RAM_NAME_LEN);
 
 	/* Dump memory header */
 	offset += qed_grc_dump_mem_hdr(p_hwfn,
-- 
1.8.3.1

Re: [PATCH net-next] qed: Fix copying 2 strings

[David Miller]

From: Denis Bolotin <denis.bolotin@cavium.com>
Date: Tue, 24 Apr 2018 15:32:53 +0300

> The strscpy() was a recent fix (net: qed: use correct strncpy() size) to
> prevent passing the length of the source buffer to strncpy() and guarantee
> null termination.
> It misses the goal of overwriting only the first 3 characters in
> "???_BIG_RAM" and "???_RAM" while keeping the rest of the string.
> Use strncpy() with the length of 3, without null termination.
> 
> Signed-off-by: Denis Bolotin <denis.bolotin@cavium.com>
> Signed-off-by: Ariel Elior <ariel.elior@cavium.com>

Applied, thank you.