| Message ID | 20231023-strncpy-drivers-s390-cio-chsc-c-v1-1-8b76a7b83260@google.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 991a211aa99f468cd291a97b8dcb448ebc77f6c4 |
| Headers | show |
| Series | s390/cio: replace deprecated strncpy with strscpy | expand |
On Mon, Oct 23, 2023 at 07:24:38PM +0000, Justin Stitt wrote: > 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> Looks good. Reviewed-by: Kees Cook <keescook@chromium.org>
On 10/23/23 21:24, Justin Stitt wrote: > 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> LGTM. Thank you. Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com> I can push this to s390-tree and Heiko/Vasily will upstream it. ---snip---
On Mon, Oct 23, 2023 at 07:24:38PM +0000, Justin Stitt wrote: > 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(-) Applied, thank you!
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; }
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(-) --- base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c change-id: 20231023-strncpy-drivers-s390-cio-chsc-c-3bafdc7535b7 Best regards, -- Justin Stitt <justinstitt@google.com>