From 8fd9efca86d083bb6fe8676ed4edd1c626d19367 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 26 Oct 2020 17:06:13 +0100 Subject: [PATCH] scsi: libfc: Work around -Warray-bounds warning Building libfc with gcc -Warray-bounds identifies a number of cases in one file where a strncpy() is performed into a single-byte character array: In file included from include/linux/bitmap.h:9, from include/linux/cpumask.h:12, from include/linux/smp.h:13, from include/linux/lockdep.h:14, from include/linux/spinlock.h:59, from include/linux/debugobjects.h:6, from include/linux/timer.h:8, from include/scsi/libfc.h:11, from drivers/scsi/libfc/fc_elsct.c:17: In function 'strncpy', inlined from 'fc_ct_ms_fill.constprop' at drivers/scsi/libfc/fc_encode.h:235:3: include/linux/string.h:290:30: warning: '__builtin_strncpy' offset [56, 135] from the object at 'pp' is out of the bounds of referenced subobject 'value' with type '__u8[1]' {aka 'unsigned char[1]'} at offset 56 [-Warray-bounds] 290 | #define __underlying_strncpy __builtin_strncpy | ^ include/linux/string.h:300:9: note: in expansion of macro '__underlying_strncpy' 300 | return __underlying_strncpy(p, q, size); | ^~~~~~~~~~~~~~~~~~~~ This is not a bug because the 1-byte array is used as an odd way to express a variable-length data field here. I tried to convert it to a flexible-array member, but in the end could not figure out why the sizeof(struct fc_fdmi_???) are used the way they are, and how to properly convert those. Work around this instead by abstracting the string copy in a slightly higher-level function fc_ct_hdr_fill() helper that strscpy() and memset() to achieve the same result as strncpy() but does not require a zero-terminated input and does not get checked for the array overflow because gcc (so far) does not understand the behavior of strscpy(). Link: https://lore.kernel.org/r/20201026160705.3706396-2-arnd@kernel.org Signed-off-by: Arnd Bergmann Signed-off-by: Martin K. Petersen --- drivers/scsi/libfc/fc_encode.h | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/drivers/scsi/libfc/fc_encode.h b/drivers/scsi/libfc/fc_encode.h index 18203ca..602c97a 100644 --- a/drivers/scsi/libfc/fc_encode.h +++ b/drivers/scsi/libfc/fc_encode.h @@ -163,6 +163,14 @@ static inline int fc_ct_ns_fill(struct fc_lport *lport, return 0; } +static inline void fc_ct_ms_fill_attr(struct fc_fdmi_attr_entry *entry, + const char *in, size_t len) +{ + int copied = strscpy(entry->value, in, len); + if (copied > 0) + memset(entry->value, copied, len - copied); +} + /** * fc_ct_ms_fill() - Fill in a mgmt service request frame * @lport: local port. @@ -232,7 +240,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_MANUFACTURER, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_manufacturer(lport->host), FC_FDMI_HBA_ATTR_MANUFACTURER_LEN); @@ -244,7 +252,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_SERIALNUMBER, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_serial_number(lport->host), FC_FDMI_HBA_ATTR_SERIALNUMBER_LEN); @@ -256,7 +264,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_MODEL, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_model(lport->host), FC_FDMI_HBA_ATTR_MODEL_LEN); @@ -268,7 +276,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_MODELDESCRIPTION, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_model_description(lport->host), FC_FDMI_HBA_ATTR_MODELDESCR_LEN); @@ -280,7 +288,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_HARDWAREVERSION, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_hardware_version(lport->host), FC_FDMI_HBA_ATTR_HARDWAREVERSION_LEN); @@ -292,7 +300,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_DRIVERVERSION, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_driver_version(lport->host), FC_FDMI_HBA_ATTR_DRIVERVERSION_LEN); @@ -304,7 +312,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_OPTIONROMVERSION, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_optionrom_version(lport->host), FC_FDMI_HBA_ATTR_OPTIONROMVERSION_LEN); @@ -316,7 +324,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, put_unaligned_be16(FC_FDMI_HBA_ATTR_FIRMWAREVERSION, &entry->type); put_unaligned_be16(len, &entry->len); - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_firmware_version(lport->host), FC_FDMI_HBA_ATTR_FIRMWAREVERSION_LEN); @@ -411,7 +419,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, &entry->type); put_unaligned_be16(len, &entry->len); /* Use the sysfs device name */ - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, dev_name(&lport->host->shost_gendev), strnlen(dev_name(&lport->host->shost_gendev), FC_FDMI_PORT_ATTR_HOSTNAME_LEN)); @@ -425,12 +433,12 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport, &entry->type); put_unaligned_be16(len, &entry->len); if (strlen(fc_host_system_hostname(lport->host))) - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, fc_host_system_hostname(lport->host), strnlen(fc_host_system_hostname(lport->host), FC_FDMI_PORT_ATTR_HOSTNAME_LEN)); else - strncpy((char *)&entry->value, + fc_ct_ms_fill_attr(entry, init_utsname()->nodename, FC_FDMI_PORT_ATTR_HOSTNAME_LEN); break; -- 2.7.4