warnquota: Check snprintf() for overflows

GCC 8 with GNU libc 2.27 prerelease warns:

gcc -DHAVE_CONFIG_H -I.     -g -O2 -Wall -fPIC -I/usr/include/tirpc  -c -o warnquota.o warnquota.c
warnquota.c: In function ‘lookup_user’:
warnquota.c:415:29: warning: ‘%s’ directive output may be truncated writing up to 2047 bytes into a region of size 255 [-Wformat-truncation=]
  snprintf(searchbuf, 256, "(%s=%s)", config->ldap_search_attr, user);
                             ^~
warnquota.c:415:2: note: ‘snprintf’ output 4 or more bytes (assuming 2051) into a destination of size 256
  snprintf(searchbuf, 256, "(%s=%s)", config->ldap_search_attr, user);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
warnquota.c: In function ‘warn_quota’:
warnquota.c:896:51: warning: ‘%s’ directive output may be truncated writing up to 2047 bytes into a region of size 2041 [-Wformat-truncation=]
    snprintf(config->ldap_uri, CNF_BUFFER, "ldap://%s:%d", config->ldap_host, config->ldap_port);
                                                   ^~      ~~~~~~~~~~~~~~~~~
warnquota.c:896:4: note: ‘snprintf’ output between 10 and 2067 bytes into a destination of size 2048
    snprintf(config->ldap_uri, CNF_BUFFER, "ldap://%s:%d", config->ldap_host, config->ldap_port);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is patch fixes it by catching the cases when snprintf() truncates and
reporting an error.

Perfect fix would fall back into dynamically allocated buffers but
I think that would make these corner case too complicated provided
nobody had yet complained about them.

Signed-off-by: Petr Písař <ppisar@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>

0 files changed, 0 insertions, 0 deletions