packet.cc: Clear tx_flags for kernels with SKBTX_DEV_ZEROCOPY

Ensure that tx_flags is cleared for kernels which have SKBTX_DEV_ZEROCOPY when uniqueifying a packet. If the flag is not cleared, the kernel will jump to a random address when the skb is eventually freed. Signed-off-by: Kevin Paul Herbert <[email protected]>
tbarbette · Sep 26, 2012 · d0cb3ae · d0cb3ae
1 parent 22abd6d
commit d0cb3ae
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Showing 4 changed files with 73 additions and 0 deletions.
diff --git a/config-linuxmodule.h.in b/config-linuxmodule.h.in
@@ -88,6 +88,9 @@
 /* Define if 'struct skb_shared_info' has an 'ip6_frag_id' member. */
 #undef HAVE_LINUX_SKB_SHINFO_IP6_FRAG_ID
 
+/* Define if 'struct skb_shared_info' has an 'tx_flags' member defining 'SKBTX_DEV_ZEROCOPY'. */
+#undef HAVE_LINUX_SKB_SHINFO_TX_FLAGS_SKBTX_DEV_ZEROCOPY
+
 /* Define if 'struct skb_shared_info' has a 'tso_size' member. */
 #undef HAVE_LINUX_SKB_SHINFO_TSO_SIZE
 

diff --git a/configure b/configure
@@ -11369,6 +11369,63 @@ $as_echo "#define HAVE_LINUX_SKB_SHINFO_IP6_FRAG_ID 1" >>confdefs.h
 
     fi
 
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether skb_shinfo has tx_flags defining SKBTX_DEV_ZEROCOPY" >&5
+$as_echo_n "checking whether skb_shinfo has tx_flags defining SKBTX_DEV_ZEROCOPY... " >&6; }
+if ${ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#if HAVE_LINUXMODULE_2_6
+# define KBUILD_STR(s)		#s
+# define KBUILD_BASENAME	KBUILD_STR(click)
+# define KBUILD_MODNAME		KBUILD_STR(click)
+#endif
+#define new linux_new
+#define this linux_this
+#define delete linux_delete
+#define class linux_class
+#define virtual linux_virtual
+#define typename linux_typename
+#define private linux_private
+#define protected linux_protected
+#define public linux_public
+#define namespace linux_namespace
+#define false linux_false
+#define true linux_true
+#define CLICK_CXX_PROTECTED 1
+$linux_autoconf_include
+#include <asm/types.h>
+#include <linux/skbuff.h>
+int
+main ()
+{
+extern struct sk_buff *s; skb_shinfo(s)->tx_flags = SKBTX_DEV_ZEROCOPY;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy=yes
+else
+  ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy" >&5
+$as_echo "$ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy" >&6; }
+    if test $ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy = yes; then
+
+$as_echo "#define HAVE_LINUX_SKB_SHINFO_TX_FLAGS_SKBTX_DEV_ZEROCOPY 1" >>confdefs.h
+
+    fi
+
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for device polling kernel extension" >&5
 $as_echo_n "checking for device polling kernel extension... " >&6; }
 if ${ac_cv_linuxmodule_net_device_polling+:} false; then :

diff --git a/configure.in b/configure.in
@@ -1430,6 +1430,16 @@ void f1(int64_t) { // will fail if long long and int64_t are the same type
 	AC_DEFINE([HAVE_LINUX_SKB_SHINFO_IP6_FRAG_ID], [1], [Define if 'struct skb_shared_info' has an 'ip6_frag_id' member.])
     fi
 
+    AC_CACHE_CHECK([whether skb_shinfo has tx_flags defining SKBTX_DEV_ZEROCOPY], [ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy],
+	[AC_LANG_C
+	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([CLICK_LINUXMODULE_PROLOGUE()[
+#include <linux/skbuff.h>]],
+[[extern struct sk_buff *s; skb_shinfo(s)->tx_flags = SKBTX_DEV_ZEROCOPY;]])],
+	[ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy=yes], [ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy=no])])
+    if test $ac_cv_linuxmodule_skb_shinfo_tx_flags_skbtx_dev_zerocopy = yes; then
+	AC_DEFINE([HAVE_LINUX_SKB_SHINFO_TX_FLAGS_SKBTX_DEV_ZEROCOPY], [1], [Define if 'struct skb_shared_info' has an 'tx_flags' member defining 'SKBTX_DEV_ZEROCOPY'.])
+    fi
+
     AC_CACHE_CHECK([for device polling kernel extension], [ac_cv_linuxmodule_net_device_polling],
 	[AC_LANG_C
 	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([CLICK_LINUXMODULE_PROLOGUE()[

diff --git a/lib/packet.cc b/lib/packet.cc
@@ -692,6 +692,9 @@ Packet::expensive_uniqueify(int32_t extra_headroom, int32_t extra_tailroom,
 # if HAVE_LINUX_SKB_SHINFO_IP6_FRAG_ID
     nskb_shinfo->ip6_frag_id = 0;
 # endif
+# if HAVE_LINUX_SKB_SHINFO_TX_FLAGS_SKBTX_DEV_ZEROCOPY
+    nskb_shinfo->tx_flags = 0;
+# endif
 
     shift_header_annotations(old_head, extra_headroom);
     return static_cast<WritablePacket *>(this);