`strncpy` is deprecated for use on NUL-terminated destination strings [1].
In this case, strncpy is being used specifically for its NUL-padding
behavior (and has been commented as such). Moreover, the destination
string is not required to be NUL-terminated [2].
We can use a more robust and less ambiguous interface in
`memcpy_and_pad` which makes the code more readable and even eliminates
the need for that comment.
Let's also use `strnlen` instead of `strlen()` with an upper-bounds
check as this is intrinsically a part of `strnlen`.
Also included in this patch is a simple 1:1 change of `strncpy` to
`strscpy` for ipmi_ssif.c. If NUL-padding is wanted here as well then we
should opt again for `strscpy_pad`.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://lore.kernel.org/all/[email protected]/ [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: [email protected]
Cc: Kees Cook <[email protected]>
Signed-off-by: Justin Stitt <[email protected]>
---
Changes in v2:
- use memcpy_and_pad (thanks Corey)
- Link to v1: https://lore.kernel.org/r/20230912-strncpy-drivers-char-ipmi-ipmi-v1-1-cc43e0d1cae6@google.com
---
drivers/char/ipmi/ipmi_msghandler.c | 11 +++--------
drivers/char/ipmi/ipmi_ssif.c | 2 +-
2 files changed, 4 insertions(+), 9 deletions(-)
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 186f1fee7534..d6f14279684d 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -5377,20 +5377,15 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
j = 0;
while (*p) {
- int size = strlen(p);
+ int size = strnlen(p, 11);
- if (size > 11)
- size = 11;
data[0] = 0;
data[1] = 0;
data[2] = 0xf0; /* OEM event without timestamp. */
data[3] = intf->addrinfo[0].address;
data[4] = j++; /* sequence # */
- /*
- * Always give 11 bytes, so strncpy will fill
- * it with zeroes for me.
- */
- strncpy(data+5, p, 11);
+
+ memcpy_and_pad(data+5, 11, p, size, '\0');
p += size;
ipmi_panic_request_and_wait(intf, &addr, &msg);
diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
index 3b921c78ba08..edcb83765dce 100644
--- a/drivers/char/ipmi/ipmi_ssif.c
+++ b/drivers/char/ipmi/ipmi_ssif.c
@@ -1940,7 +1940,7 @@ static int new_ssif_client(int addr, char *adapter_name,
}
}
- strncpy(addr_info->binfo.type, DEVICE_NAME,
+ strscpy(addr_info->binfo.type, DEVICE_NAME,
sizeof(addr_info->binfo.type));
addr_info->binfo.addr = addr;
addr_info->binfo.platform_data = addr_info;
---
base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230912-strncpy-drivers-char-ipmi-ipmi-dda47b3773fd
Best regards,
--
Justin Stitt <[email protected]>