[tor-commits] [tor/master] Enable -Wnull-dereference (GCC >=6.1), and fix the easy cases
nickm at torproject.org
nickm at torproject.org
Sat Jun 11 14:16:58 UTC 2016
commit 4f8086fb20e93c477f033f58da17aa31b9c29fd6
Author: Nick Mathewson <nickm at torproject.org>
Date: Mon May 30 11:12:58 2016 -0400
Enable -Wnull-dereference (GCC >=6.1), and fix the easy cases
This warning, IIUC, means that the compiler doesn't like it when it
sees a NULL check _after_ we've already dereferenced the
variable. In such cases, it considers itself free to eliminate the
NULL check.
There are a couple of tricky cases:
One was the case related to the fact that tor_addr_to_in6() can
return NULL if it gets a non-AF_INET6 address. The fix was to
create a variant which asserts on the address type, and never
returns NULL.
---
configure.ac | 1 +
src/common/address.c | 3 ++-
src/common/address.h | 16 +++++++++++++---
src/ext/ht.h | 2 ++
src/or/channeltls.c | 1 +
src/or/connection.c | 2 +-
src/or/geoip.c | 8 ++++----
src/test/test_bt_cl.c | 6 ++++++
8 files changed, 30 insertions(+), 9 deletions(-)
diff --git a/configure.ac b/configure.ac
index ec56e02..4878d2b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1776,6 +1776,7 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
if test "x$have_gcc6" = "xyes"; then
CFLAGS="$CFLAGS -Wignored-attributes -Wshift-negative-value -Wshift-overflow=2"
+ CFLAGS="$CFLAGS -Wnull-dereference"
fi
if test "x$have_shorten64_flag" = "xyes"; then
diff --git a/src/common/address.c b/src/common/address.c
index a6e0f3f..759b20a 100644
--- a/src/common/address.c
+++ b/src/common/address.c
@@ -131,7 +131,8 @@ tor_addr_to_sockaddr(const tor_addr_t *a,
#endif
sin6->sin6_family = AF_INET6;
sin6->sin6_port = htons(port);
- memcpy(&sin6->sin6_addr, tor_addr_to_in6(a), sizeof(struct in6_addr));
+ memcpy(&sin6->sin6_addr, tor_addr_to_in6_assert(a),
+ sizeof(struct in6_addr));
return sizeof(struct sockaddr_in6);
} else {
return 0;
diff --git a/src/common/address.h b/src/common/address.h
index 3de67e1..3f0bb52 100644
--- a/src/common/address.h
+++ b/src/common/address.h
@@ -74,6 +74,7 @@ typedef struct tor_addr_port_t
#define TOR_ADDR_NULL {AF_UNSPEC, {0}}
static inline const struct in6_addr *tor_addr_to_in6(const tor_addr_t *a);
+static inline const struct in6_addr *tor_addr_to_in6_assert(const tor_addr_t *a);
static inline uint32_t tor_addr_to_ipv4n(const tor_addr_t *a);
static inline uint32_t tor_addr_to_ipv4h(const tor_addr_t *a);
static inline uint32_t tor_addr_to_mapped_ipv4h(const tor_addr_t *a);
@@ -97,21 +98,30 @@ tor_addr_to_in6(const tor_addr_t *a)
return a->family == AF_INET6 ? &a->addr.in6_addr : NULL;
}
+/** As tor_addr_to_in6, but assert that the address truly is an IPv6 address. */
+static inline const struct in6_addr *
+tor_addr_to_in6_assert(const tor_addr_t *a)
+{
+ tor_assert(a->family == AF_INET6);
+ return &a->addr.in6_addr;
+}
+
/** Given an IPv6 address <b>x</b>, yield it as an array of uint8_t.
*
* Requires that <b>x</b> is actually an IPv6 address.
*/
-#define tor_addr_to_in6_addr8(x) tor_addr_to_in6(x)->s6_addr
+#define tor_addr_to_in6_addr8(x) tor_addr_to_in6_assert(x)->s6_addr
+
/** Given an IPv6 address <b>x</b>, yield it as an array of uint16_t.
*
* Requires that <b>x</b> is actually an IPv6 address.
*/
-#define tor_addr_to_in6_addr16(x) S6_ADDR16(*tor_addr_to_in6(x))
+#define tor_addr_to_in6_addr16(x) S6_ADDR16(*tor_addr_to_in6_assert(x))
/** Given an IPv6 address <b>x</b>, yield it as an array of uint32_t.
*
* Requires that <b>x</b> is actually an IPv6 address.
*/
-#define tor_addr_to_in6_addr32(x) S6_ADDR32(*tor_addr_to_in6(x))
+#define tor_addr_to_in6_addr32(x) S6_ADDR32(*tor_addr_to_in6_assert(x))
/** Return an IPv4 address in network order for <b>a</b>, or 0 if
* <b>a</b> is not an IPv4 address. */
diff --git a/src/ext/ht.h b/src/ext/ht.h
index 28d1fe4..1b6cbe6 100644
--- a/src/ext/ht.h
+++ b/src/ext/ht.h
@@ -203,6 +203,7 @@ ht_string_hash(const char *s)
name##_HT_GROW(head, head->hth_n_entries+1); \
HT_SET_HASH_(elm, field, hashfn); \
p = name##_HT_FIND_P_(head, elm); \
+ HT_ASSERT_(p != NULL); /* this holds because we called HT_GROW */ \
r = *p; \
*p = elm; \
if (r && (r!=elm)) { \
@@ -470,6 +471,7 @@ ht_string_hash(const char *s)
name##_HT_GROW(var##_head_, var##_head_->hth_n_entries+1); \
HT_SET_HASH_((elm), field, hashfn); \
var = name##_HT_FIND_P_(var##_head_, (elm)); \
+ HT_ASSERT_(var); /* Holds because we called HT_GROW */ \
if (*var) { \
y; \
} else { \
diff --git a/src/or/channeltls.c b/src/or/channeltls.c
index 2128b09..293f010 100644
--- a/src/or/channeltls.c
+++ b/src/or/channeltls.c
@@ -797,6 +797,7 @@ static int
channel_tls_write_packed_cell_method(channel_t *chan,
packed_cell_t *packed_cell)
{
+ tor_assert(chan);
channel_tls_t *tlschan = BASE_CHAN_TO_TLS(chan);
size_t cell_network_size = get_cell_network_size(chan->wide_circ_ids);
int written = 0;
diff --git a/src/or/connection.c b/src/or/connection.c
index e70b897..86ed2fb 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -2240,7 +2240,7 @@ connection_send_socks5_connect(connection_t *conn)
} else { /* AF_INET6 */
buf[3] = 4;
reqsize += 16;
- memcpy(buf + 4, tor_addr_to_in6(&conn->addr), 16);
+ memcpy(buf + 4, tor_addr_to_in6_addr8(&conn->addr), 16);
memcpy(buf + 20, &port, 2);
}
diff --git a/src/or/geoip.c b/src/or/geoip.c
index b563db0..24ec9b7 100644
--- a/src/or/geoip.c
+++ b/src/or/geoip.c
@@ -80,9 +80,9 @@ geoip_add_entry(const tor_addr_t *low, const tor_addr_t *high,
intptr_t idx;
void *idxplus1_;
- if (tor_addr_family(low) != tor_addr_family(high))
+ IF_BUG_ONCE(tor_addr_family(low) != tor_addr_family(high))
return;
- if (tor_addr_compare(high, low, CMP_EXACT) < 0)
+ IF_BUG_ONCE(tor_addr_compare(high, low, CMP_EXACT) < 0)
return;
idxplus1_ = strmap_get_lc(country_idxplus1_by_lc_code, country);
@@ -110,8 +110,8 @@ geoip_add_entry(const tor_addr_t *low, const tor_addr_t *high,
smartlist_add(geoip_ipv4_entries, ent);
} else if (tor_addr_family(low) == AF_INET6) {
geoip_ipv6_entry_t *ent = tor_malloc_zero(sizeof(geoip_ipv6_entry_t));
- ent->ip_low = *tor_addr_to_in6(low);
- ent->ip_high = *tor_addr_to_in6(high);
+ ent->ip_low = *tor_addr_to_in6_assert(low);
+ ent->ip_high = *tor_addr_to_in6_assert(high);
ent->country = idx;
smartlist_add(geoip_ipv6_entries, ent);
}
diff --git a/src/test/test_bt_cl.c b/src/test/test_bt_cl.c
index 2f5e50f..ec03ced 100644
--- a/src/test/test_bt_cl.c
+++ b/src/test/test_bt_cl.c
@@ -28,6 +28,9 @@ int a_tangled_web(int x) NOINLINE;
int we_weave(int x) NOINLINE;
static void abort_handler(int s) NORETURN;
+#if GCC_VERSION >= 601
+DISABLE_GCC_WARNING(null-dereference)
+#endif
int
crash(int x)
{
@@ -47,6 +50,9 @@ crash(int x)
crashtype *= x;
return crashtype;
}
+#if GCC_VERSION >= 601
+ENABLE_GCC_WARNING(null-dereference)
+#endif
int
oh_what(int x)
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