BUG printk with not null-terminated string in driver /drivers/acpi/osl.c

[Alexander Strakh]

In driver drivers/acpi/osl.c in function acpi_osi_setup:
1. If in line 555 *osi_additional_string == 0 then we goto line 1039
2. In line 1039: if length of str > OSI_STRING_LENGTH_MAX then
osi_additional_string not have 0 at the end.
3. In line 1040 printk called with not null-terminated string.
1026 int __init acpi_osi_setup(char *str)
1027 {
1028 if (str == NULL || *str == '\0') {
1029 printk(KERN_INFO PREFIX "_OSI method disabled\n");
1030 acpi_gbl_create_osi_method = FALSE;
1031 } else if (!strcmp("!Linux", str)) {
1032 acpi_cmdline_osi_linux(0); /* !enable */
1033 } else if (*str == '!') {
1034 if (acpi_osi_invalidate(++str) == AE_OK)
1035 printk(KERN_INFO PREFIX "Deleted _OSI(%s)\n",
str);
1036 } else if (!strcmp("Linux", str)) {
1037 acpi_cmdline_osi_linux(1); /* enable */
1038 } else if (*osi_additional_string == '\0') {
1039 strncpy(osi_additional_string, str,
OSI_STRING_LENGTH_MAX);
1040 printk(KERN_INFO PREFIX "Added _OSI(%s)\n", str);
1041 }
1042
1043 return 1;
1044 }

Found by Linux Device Drivers Verification (Svace detector)

Add terminate symbol for string in any cases.

Signed-off-by: Alexander Strakh <str...@ispras.ru>

---
diff --git a/./0000/drivers/acpi/osl.c b/./0001/drivers/acpi/osl.c
index 02e8464..9c759f8 100644
--- a/./0000/drivers/acpi/osl.c
+++ b/./0001/drivers/acpi/osl.c
@@ -1037,6 +1037,7 @@ int __init acpi_osi_setup(char *str)
acpi_cmdline_osi_linux(1); /* enable */
} else if (*osi_additional_string == '\0') {
strncpy(osi_additional_string, str, OSI_STRING_LENGTH_MAX);
+ osi_additional_string[OSI_STRING_LENGTH_MAX - 1] = 0;
printk(KERN_INFO PREFIX "Added _OSI(%s)\n", str);
}

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[Björn Steinbrink]

On 2009.12.22 18:46:02 +0000, Alexander Strakh wrote:
> In driver drivers/acpi/osl.c in function acpi_osi_setup:
> 1. If in line 555 *osi_additional_string == 0 then we goto line 1039

I guess that's meant to be line 1038?

> 2. In line 1039: if length of str > OSI_STRING_LENGTH_MAX then
> osi_additional_string not have 0 at the end.
> 3. In line 1040 printk called with not null-terminated string.

That printk uses str, not osi_additional_string.

> diff --git a/./0000/drivers/acpi/osl.c b/./0001/drivers/acpi/osl.c
> index 02e8464..9c759f8 100644
> --- a/./0000/drivers/acpi/osl.c
> +++ b/./0001/drivers/acpi/osl.c
> @@ -1037,6 +1037,7 @@ int __init acpi_osi_setup(char *str)
> acpi_cmdline_osi_linux(1); /* enable */
> } else if (*osi_additional_string == '\0') {
> strncpy(osi_additional_string, str, OSI_STRING_LENGTH_MAX);
> + osi_additional_string[OSI_STRING_LENGTH_MAX - 1] = 0;

That will break the test in acpi_os_validate_interface for strings
longer than OSI_STRING_LENGTH_MAX (incl. the NUL byte). And that's the
only other user of osi_additional_string and doesn't require the
terminating NUL byte. So this shouldn't be needed.

Bj�rn