kern/57829: pci_subr.c: gcc -O failed 'str' may be used uninitialized in this function

[hashikaw%mail.ru@localhost]

>Number:         57829
>Category:       kern
>Synopsis:       pci_subr.c: gcc -O failed 'str' may be used uninitialized in this function
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jan 08 06:10:00 +0000 2024
>Originator:     Kouichi Hashikawa
>Release:        9.3-RELEASE, 10.0-RC2, current
>Organization:
>Environment:
>Description:
gcc -O failed to compile pci_subr.c with 'str' may be used uninitialized in this function.
(10.0-RC2, pci_subr.c is 1.242).

--- pci_subr.o ---
/usr/src/sys/dev/pci/pci_subr.c: In function 'pci_conf_print_type0':
/usr/src/sys/dev/pci/pci_subr.c:4783:2: error: 'str' may be used uninitialized in this function [-Werror=maybe-uninitialized]
 4783 |  printf("%s\n", str);
      |  ^~~~~~~~~~~~~~~~~~~

I think 9.3 and current have same problem.

>How-To-Repeat:

>Fix:
I apply following patch.

--- src/sys/dev/pci/pci_subr.c-1242     2022-02-10 14:20:10.212466898 +0900
+++ src/sys/dev/pci/pci_subr.c  2024-01-08 14:43:49.139272695 +0900
@@ -4729,7 +4729,7 @@
 {
        int off, width;
        pcireg_t rval;
-       const char *str;
+       const char *str = NULL;
 
        for (off = PCI_MAPREG_START; off < PCI_MAPREG_END; off += width) {
 #ifdef _KERNEL
@@ -4780,7 +4780,8 @@
                    "Valid and trusted contents";
                break;
        }
-       printf("%s\n", str);
+       if (str != NULL)
+           printf("%s\n", str);
        printf("      Validation Details: 0x%x\n",
            PCIREG_SHIFTOUT(rval, PCI_MAPREG_ROM_VALID_DETAIL));