DNS: Fix a NULL pointer deref when trying to read an error key [CVE-2011-1076]
When a DNS resolver key is instantiated with an error indication, attempts to read that key will result in an oops because user_read() is expecting there to be a payload - and there isn't one [CVE-2011-1076]. Give the DNS resolver key its own read handler that returns the error cached in key->type_data.x[0] as an error rather than crashing. Also make the kenter() at the beginning of dns_resolver_instantiate() limit the amount of data it prints, since the data is not necessarily NUL-terminated. The buggy code was added in: commit 4a2d7892 Author: Wang Lei <wang840925@gmail.com> Date: Wed Aug 11 09:37:58 2010 +0100 Subject: DNS: If the DNS server returns an error, allow that to be cached [ver #2] This can trivially be reproduced by any user with the following program compiled with -lkeyutils: #include <stdlib.h> #include <keyutils.h> #include <err.h> static char payload[] = "#dnserr...
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