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Date: Thu, 12 Oct 2023 18:35:41 +0000
From: Justin Stitt <>
To: Ariel Elior <>, Manish Chopra <>, 
	"David S. Miller" <>, Eric Dumazet <>, 
	Jakub Kicinski <>, Paolo Abeni <>
Cc:,,, Kees Cook <>, 
	Justin Stitt <>
Subject: [PATCH v2] qed: replace uses of strncpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string

This patch eliminates three uses of strncpy():

Firstly, `dest` is expected to be NUL-terminated which is evident by the
manual setting of a NUL-byte at size - 1. For this use specifically,
strscpy() is a viable replacement due to the fact that it guarantees
NUL-termination on the destination buffer.

The next two cases should simply be memcpy() as the size of the src
string is always 3 and the destination string just wants the first 3
bytes changed.

To be clear, there are no buffer overread bugs in the current code as
the sizes and offsets are carefully managed such that buffers are
NUL-terminated. However, with these changes, the code is now more robust
and less ambiguous (and hopefully easier to read).

Link: [1]
Link: [2]
Cc: Kees Cook <>
Signed-off-by: Justin Stitt <>
Changes in v2:
- prefer memcpy to snprintf (thanks Kees)
- Link to v1:
Note: build-tested only.

Found with: $ rg "strncpy\("
 drivers/net/ethernet/qlogic/qed/qed_debug.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_debug.c b/drivers/net/ethernet/qlogic/qed/qed_debug.c
index cdcead614e9f..f67be4b8ad43 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_debug.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_debug.c
@@ -3204,8 +3204,8 @@ 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;
-	strncpy(type_name, big_ram->instance_name, BIG_RAM_NAME_LEN);
-	strncpy(mem_name, big_ram->instance_name, BIG_RAM_NAME_LEN);
+	memcpy(type_name, big_ram->instance_name, BIG_RAM_NAME_LEN);
+	memcpy(mem_name, big_ram->instance_name, BIG_RAM_NAME_LEN);
 	/* Dump memory header */
 	offset += qed_grc_dump_mem_hdr(p_hwfn,
@@ -6359,8 +6359,7 @@ static void qed_read_str_from_buf(void *buf, u32 *offset, u32 size, char *dest)
 	const char *source_str = &((const char *)buf)[*offset];
-	strncpy(dest, source_str, size);
-	dest[size - 1] = '\0';
+	strscpy(dest, source_str, size);
 	*offset += size;

base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231011-strncpy-drivers-net-ethernet-qlogic-qed-qed_debug-c-211d594201e4

Best regards,
Justin Stitt <>

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