scsi: libfc: Fix potential buffer overflow in fc_ct_ms_fill()

The fc_ct_ms_fill() helper currently formats the OS name and version
into entry->value using "%s v%s". Since init_utsname()->sysname and
->release are unbounded strings, snprintf() may attempt to write more
than FC_FDMI_HBA_ATTR_OSNAMEVERSION_LEN bytes, triggering a
-Wformat-truncation warning with W=1.

In file included from drivers/scsi/libfc/fc_elsct.c:18:
drivers/scsi/libfc/fc_encode.h: In function ‘fc_ct_ms_fill.constprop’:
drivers/scsi/libfc/fc_encode.h:359:30: error: ‘%s’ directive output may
be truncated writing up to 64 bytes into a region of size between 62
and 126 [-Werror=format-truncation=]
  359 |                         "%s v%s",
      |                              ^~
  360 |                         init_utsname()->sysname,
  361 |                         init_utsname()->release);
      |                         ~~~~~~~~~~~~~~~~~~~~~~~
drivers/scsi/libfc/fc_encode.h:357:17: note: ‘snprintf’ output between
3 and 131 bytes into a destination of size 128
  357 |                 snprintf((char *)&entry->value,
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  358 |                         FC_FDMI_HBA_ATTR_OSNAMEVERSION_LEN,
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  359 |                         "%s v%s",
      |                         ~~~~~~~~~
  360 |                         init_utsname()->sysname,
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~
  361 |                         init_utsname()->release);
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by using "%.62s v%.62s", which ensures sysname and release are
truncated to fit within the 128-byte field defined by
FC_FDMI_HBA_ATTR_OSNAMEVERSION_LEN.

[mkp: clarified commit description]

Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/libfc/fc_encode.h b/drivers/scsi/libfc/fc_encode.h
index 02e31db31d68e623462d7c4fe44095ec29af8855..e046091a549aeaa9d90b0a209c5bb37d41c36713 100644 (file)
--- a/drivers/scsi/libfc/fc_encode.h
+++ b/drivers/scsi/libfc/fc_encode.h
@@ -356,7 +356,7 @@ static inline int fc_ct_ms_fill(struct fc_lport *lport,
                put_unaligned_be16(len, &entry->len);
                snprintf((char *)&entry->value,
                        FC_FDMI_HBA_ATTR_OSNAMEVERSION_LEN,
-                       "%s v%s",
+                       "%.62s v%.62s",
                        init_utsname()->sysname,
                        init_utsname()->release);