kernel/audit.c control character detection is off-by-one
Hello,
According to my understanding there is an off-by-one bug in the
function:
audit_string_contains_control()
in:
kernel/audit.c
Patch is included.
I do not know from how many places the function is called from, but for
example, SELinux Access Vector Cache tries to log untrusted filenames via
call path:
avc_audit()
audit_log_untrustedstring()
audit_log_n_untrustedstring()
audit_string_contains_control()
If audit_string_contains_control() detects control characters, then the
string is hex-encoded. But the hex=0x7f dec=127, DEL-character, is not
detected.
I guess this could have at least some minor security implications, since a
user can create a filename with 0x7f in it, causing logged filename to
possibly look different when someone reads it on the terminal.
Signed-off-by: Vesa-Matti Kari <vmkari@cc.helsinki.fi>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/audit.c b/kernel/audit.c
index e092f1c..6d90318 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1366,7 +1366,7 @@
{
const unsigned char *p;
for (p = string; p < (const unsigned char *)string + len && *p; p++) {
- if (*p == '"' || *p < 0x21 || *p > 0x7f)
+ if (*p == '"' || *p < 0x21 || *p > 0x7e)
return 1;
}
return 0;