| Message ID | 20200923083700.44624-4-jwi@linux.ibm.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | s390/qeth: updates 2020-09-23 | expand |
From: Julian Wiedmann > Sent: 23 September 2020 09:37 > > Indicate the max number of to-be-parsed characters, and avoid copying > the address sub-string. > > Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com> > --- > drivers/s390/net/qeth_l3_sys.c | 27 ++++++++++++++------------- > 1 file changed, 14 insertions(+), 13 deletions(-) > > diff --git a/drivers/s390/net/qeth_l3_sys.c b/drivers/s390/net/qeth_l3_sys.c > index ca9c95b6bf35..05fa986e30fc 100644 > --- a/drivers/s390/net/qeth_l3_sys.c > +++ b/drivers/s390/net/qeth_l3_sys.c > @@ -409,21 +409,22 @@ static ssize_t qeth_l3_dev_ipato_add4_show(struct device *dev, > static int qeth_l3_parse_ipatoe(const char *buf, enum qeth_prot_versions proto, > u8 *addr, int *mask_bits) > { > - const char *start, *end; > - char *tmp; > - char buffer[40] = {0, }; > + const char *start; > + char *sep, *tmp; > + int rc; > > - start = buf; > - /* get address string */ > - end = strchr(start, '/'); > - if (!end || (end - start >= 40)) { > + /* Expected input pattern: %addr/%mask */ > + sep = strnchr(buf, 40, '/'); > + if (!sep) > return -EINVAL; > - } > - strncpy(buffer, start, end - start); > - if (qeth_l3_string_to_ipaddr(buffer, proto, addr)) { > - return -EINVAL; > - } > - start = end + 1; > + > + /* Terminate the %addr sub-string, and parse it: */ > + *sep = '\0'; Is it valid to write into the input buffer here? > + rc = qeth_l3_string_to_ipaddr(buf, proto, addr); > + if (rc) > + return rc; > + > + start = sep + 1; > *mask_bits = simple_strtoul(start, &tmp, 10); The use of strnchr() rather implies that the input buffer may not be '\0' terminated. If that is true then you've just run off the end of the input buffer. > if (!strlen(start) || > (tmp == start) || Hmmm... delete the strlen() clause. It ought to test start[0], but the 'tmp == start' test covers that case. I don't understand why simple_strtoul() is deprecated. I don't recall any of the replacements returning the address of the terminating character. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On 23.09.20 12:55, David Laight wrote: > From: Julian Wiedmann >> Sent: 23 September 2020 09:37 >> >> Indicate the max number of to-be-parsed characters, and avoid copying >> the address sub-string. >> >> Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com> >> --- >> drivers/s390/net/qeth_l3_sys.c | 27 ++++++++++++++------------- >> 1 file changed, 14 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/s390/net/qeth_l3_sys.c b/drivers/s390/net/qeth_l3_sys.c >> index ca9c95b6bf35..05fa986e30fc 100644 >> --- a/drivers/s390/net/qeth_l3_sys.c >> +++ b/drivers/s390/net/qeth_l3_sys.c >> @@ -409,21 +409,22 @@ static ssize_t qeth_l3_dev_ipato_add4_show(struct device *dev, >> static int qeth_l3_parse_ipatoe(const char *buf, enum qeth_prot_versions proto, >> u8 *addr, int *mask_bits) >> { >> - const char *start, *end; >> - char *tmp; >> - char buffer[40] = {0, }; >> + const char *start; >> + char *sep, *tmp; >> + int rc; >> >> - start = buf; >> - /* get address string */ >> - end = strchr(start, '/'); >> - if (!end || (end - start >= 40)) { >> + /* Expected input pattern: %addr/%mask */ >> + sep = strnchr(buf, 40, '/'); >> + if (!sep) >> return -EINVAL; >> - } >> - strncpy(buffer, start, end - start); >> - if (qeth_l3_string_to_ipaddr(buffer, proto, addr)) { >> - return -EINVAL; >> - } >> - start = end + 1; >> + >> + /* Terminate the %addr sub-string, and parse it: */ >> + *sep = '\0'; > > Is it valid to write into the input buffer here? > It's a private buffer that was handed to us by the kernfs write code. >> + rc = qeth_l3_string_to_ipaddr(buf, proto, addr); >> + if (rc) >> + return rc; >> + >> + start = sep + 1; >> *mask_bits = simple_strtoul(start, &tmp, 10); > > The use of strnchr() rather implies that the input > buffer may not be '\0' terminated. It's a kernfs write buffer, so guaranteed to be terminated. > If that is true then you've just run off the end of the > input buffer. > >> if (!strlen(start) || >> (tmp == start) || > > Hmmm... delete the strlen() clause. > It ought to test start[0], but the 'tmp == start' test > covers that case. > See the next patch in this series, all this goes away. > I don't understand why simple_strtoul() is deprecated. > I don't recall any of the replacements returning the > address of the terminating character. > > David > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales) > b
diff --git a/drivers/s390/net/qeth_l3_sys.c b/drivers/s390/net/qeth_l3_sys.c index ca9c95b6bf35..05fa986e30fc 100644 --- a/drivers/s390/net/qeth_l3_sys.c +++ b/drivers/s390/net/qeth_l3_sys.c @@ -409,21 +409,22 @@ static ssize_t qeth_l3_dev_ipato_add4_show(struct device *dev, static int qeth_l3_parse_ipatoe(const char *buf, enum qeth_prot_versions proto, u8 *addr, int *mask_bits) { - const char *start, *end; - char *tmp; - char buffer[40] = {0, }; + const char *start; + char *sep, *tmp; + int rc; - start = buf; - /* get address string */ - end = strchr(start, '/'); - if (!end || (end - start >= 40)) { + /* Expected input pattern: %addr/%mask */ + sep = strnchr(buf, 40, '/'); + if (!sep) return -EINVAL; - } - strncpy(buffer, start, end - start); - if (qeth_l3_string_to_ipaddr(buffer, proto, addr)) { - return -EINVAL; - } - start = end + 1; + + /* Terminate the %addr sub-string, and parse it: */ + *sep = '\0'; + rc = qeth_l3_string_to_ipaddr(buf, proto, addr); + if (rc) + return rc; + + start = sep + 1; *mask_bits = simple_strtoul(start, &tmp, 10); if (!strlen(start) || (tmp == start) ||
Indicate the max number of to-be-parsed characters, and avoid copying the address sub-string. Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com> --- drivers/s390/net/qeth_l3_sys.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-)