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From eeef53917864600e0f5ac42ce5c3d884967012a1 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
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Date: Mon, 5 Feb 2018 10:31:47 +0100
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Subject: [PATCH 1/2] warnquota: Check snprintf() for overflows
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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GCC 8 with GNU libc 2.27 prerelease warns:
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gcc -DHAVE_CONFIG_H -I. -g -O2 -Wall -fPIC -I/usr/include/tirpc -c -o warnquota.o warnquota.c
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warnquota.c: In function ‘lookup_user’:
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warnquota.c:415:29: warning: ‘%s’ directive output may be truncated writing up to 2047 bytes into a region of size 255 [-Wformat-truncation=]
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snprintf(searchbuf, 256, "(%s=%s)", config->ldap_search_attr, user);
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^~
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warnquota.c:415:2: note: ‘snprintf’ output 4 or more bytes (assuming 2051) into a destination of size 256
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snprintf(searchbuf, 256, "(%s=%s)", config->ldap_search_attr, user);
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^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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warnquota.c: In function ‘warn_quota’:
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warnquota.c:896:51: warning: ‘%s’ directive output may be truncated writing up to 2047 bytes into a region of size 2041 [-Wformat-truncation=]
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snprintf(config->ldap_uri, CNF_BUFFER, "ldap://%s:%d", config->ldap_host, config->ldap_port);
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^~ ~~~~~~~~~~~~~~~~~
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warnquota.c:896:4: note: ‘snprintf’ output between 10 and 2067 bytes into a destination of size 2048
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snprintf(config->ldap_uri, CNF_BUFFER, "ldap://%s:%d", config->ldap_host, config->ldap_port);
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^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This is patch fixes it by catching the cases when snprintf() truncates and
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reporting an error.
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Perfect fix would fall back into dynamically allocated buffers but
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I think that would make these corner case too complicated provided
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nobody had yet complained about them.
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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warnquota.c | 17 +++++++++++++++--
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1 file changed, 15 insertions(+), 2 deletions(-)
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diff --git a/warnquota.c b/warnquota.c
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index 073c45e..bc11055 100644
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--- a/warnquota.c
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+++ b/warnquota.c
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@@ -412,7 +412,13 @@ static char *lookup_user(struct configparams *config, char *user)
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}
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/* search for the offender_name in ldap */
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- snprintf(searchbuf, 256, "(%s=%s)", config->ldap_search_attr, user);
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+ if (256 <= snprintf(searchbuf, 256, "(%s=%s)", config->ldap_search_attr,
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+ user)) {
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+ errstr(_("Could not format LDAP search filter for %s user and "
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+ "%s search attribute due to excessive length.\n"),
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+ user, config->ldap_search_attr);
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+ return NULL;
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+ }
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ret = ldap_search_ext_s(ldapconn,
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config->ldap_basedn, LDAP_SCOPE_SUBTREE,
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searchbuf, NULL, 0, NULL, NULL, NULL,
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@@ -893,7 +899,14 @@ cc_parse_err:
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if (config->use_ldap_mail)
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{
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if (!config->ldap_uri[0]) {
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- snprintf(config->ldap_uri, CNF_BUFFER, "ldap://%s:%d", config->ldap_host, config->ldap_port);
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+ if (CNF_BUFFER <= snprintf(config->ldap_uri, CNF_BUFFER,
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+ "ldap://%s:%d", config->ldap_host,
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+ config->ldap_port)) {
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+ errstr(_("Could not format LDAP URI because "
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+ "it's longer than %d bytes.\n"),
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+ CNF_BUFFER);
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+ return -1;
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+ }
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errstr(_("LDAP library version >= 2.3 detected. Please use LDAP_URI instead of hostname and port.\nGenerated URI %s\n"), config->ldap_uri);
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}
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}
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--
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2.13.6
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