Messages in this thread Patch in this message | | | Date | Mon, 23 Oct 2023 19:24:38 +0000 | Subject | [PATCH] s390/cio: replace deprecated strncpy with strscpy | From | Justin Stitt <> |
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strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces.
We expect both `params` and `id` to be NUL-terminated based on their usage with format strings:
format_node_data(iuparams, iunodeid, &lir->incident_node); format_node_data(auparams, aunodeid, &lir->attached_node);
switch (lir->iq.class) { case LIR_IQ_CLASS_DEGRADED: pr_warn("Link degraded: RS=%02x RSID=%04x IC=%02x " "IUPARAMS=%s IUNODEID=%s AUPARAMS=%s AUNODEID=%s\n", sei_area->rs, sei_area->rsid, lir->ic, iuparams, iunodeid, auparams, aunodeid);
NUL-padding is not required as both `params` and `id` have been memset to 0:
memset(params, 0, PARAMS_LEN); memset(id, 0, NODEID_LEN);
Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding.
Note that there's no overread bugs in the current implementation as the string literal "n/a" has a size much smaller than PARAMS_LEN or NODEID_LEN. Nonetheless, let's favor strscpy().
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt <justinstitt@google.com> --- Note: build-tested only.
Found with: $ rg "strncpy\(" --- drivers/s390/cio/chsc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c index 0abd77f4b664..9319f448a6e2 100644 --- a/drivers/s390/cio/chsc.c +++ b/drivers/s390/cio/chsc.c @@ -393,8 +393,8 @@ static void format_node_data(char *params, char *id, struct node_descriptor *nd) memset(id, 0, NODEID_LEN); if (nd->validity != ND_VALIDITY_VALID) { - strncpy(params, "n/a", PARAMS_LEN - 1); - strncpy(id, "n/a", NODEID_LEN - 1); + strscpy(params, "n/a", PARAMS_LEN); + strscpy(id, "n/a", NODEID_LEN); return; } --- base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c change-id: 20231023-strncpy-drivers-s390-cio-chsc-c-3bafdc7535b7 Best regards, -- Justin Stitt <justinstitt@google.com>
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