Bug found by Herb. blkcnt_t st_ex_blksize is defined as a signed value. When it is

on a 32-bit system and defined as a long, then inside vfswrap_get_alloc_size()
we cast to a uint64_t. This sign-extends when converting to unsigned,
so if the high bit of st_ex_blksize is set we return insane values to clients.

3 files changed, 53 insertions, 0 deletions

diff --git a/source3/configure.in b/source3/configure.in
index 8e44c23da0..98714d5dd2 100644
--- a/source3/configure.in
+++ b/source3/configure.in
@@ -2936,6 +2936,32 @@ fi
 
 AC_CHECK_TYPES([blksize_t, blkcnt_t], [], [], [[#include <sys/stat.h>]])
 
+AC_CACHE_CHECK([for 32 bit blkcnt_t],samba_cv_SIZEOF_BLKCNT_T_4,[
+AC_TRY_RUN([
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+#include <stdio.h>
+#include <sys/stat.h>
+main() { exit((sizeof(blkcnt_t) == 4) ? 0 : 1); }],
+samba_cv_SIZEOF_BLKCNT_T_4=yes,samba_cv_SIZEOF_BLKCNT_T_4=no,samba_cv_SIZEOF_BLKCNT_T_4=cross)])
+if test x"$samba_cv_SIZEOF_BLKCNT_T_4" = x"yes"; then
+    AC_DEFINE(SIZEOF_BLKCNT_T_4,1,[The size of the 'blkcnt_t' type])
+fi
+
+AC_CACHE_CHECK([for 64 bit blkcnt_t],samba_cv_SIZEOF_BLKCNT_T_8,[
+AC_TRY_RUN([
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+#include <stdio.h>
+#include <sys/stat.h>
+main() { exit((sizeof(blkcnt_t) == 8) ? 0 : 1); }],
+samba_cv_SIZEOF_BLKCNT_T_8=yes,samba_cv_SIZEOF_BLKCNT_T_8=no,samba_cv_SIZEOF_BLKCNT_T_8=cross)])
+if test x"$samba_cv_SIZEOF_BLKCNT_T_8" = x"yes"; then
+    AC_DEFINE(SIZEOF_BLKCNT_T_8,1,[The size of the 'blkcnt_t' type])
+fi
+
 AC_CACHE_CHECK([for st_blksize in struct stat],samba_cv_HAVE_STAT_ST_BLKSIZE,[
 AC_TRY_COMPILE([#include <sys/types.h>
 #include <sys/stat.h>
diff --git a/source3/modules/vfs_default.c b/source3/modules/vfs_default.c
index cf2bdb05c5..915eae67d3 100644
--- a/source3/modules/vfs_default.c
+++ b/source3/modules/vfs_default.c
@@ -1119,7 +1119,20 @@ static uint64_t vfswrap_get_alloc_size(vfs_handle_struct *handle,
 	}
 
 #if defined(HAVE_STAT_ST_BLOCKS) && defined(STAT_ST_BLOCKSIZE)
+	/* The type of st_blocksize is blkcnt_t which *MUST* be
+	   signed (according to POSIX) and can be less than 64-bits.
+	   Ensure when we're converting to 64 bits wide we don't
+	   sign extend. */
+#if defined(SIZEOF_BLKCNT_T_8)
 	result = (uint64_t)STAT_ST_BLOCKSIZE * (uint64_t)sbuf->st_ex_blocks;
+#elif defined(SIZEOF_BLKCNT_T_4)
+	{
+		uint64_t bs = ((uint64_t)sbuf->st_ex_blocks) & 0xFFFFFFFFLL;
+		result = (uint64_t)STAT_ST_BLOCKSIZE * bs;
+	}
+#else
+#error SIZEOF_BLKCNT_T_NOT_A_SUPPORTED_VALUE
+#endif
 #else
 	result = get_file_size_stat(sbuf);
 #endif
diff --git a/source3/wscript b/source3/wscript
index 9a9757a7b2..28ef0d932f 100644
--- a/source3/wscript
+++ b/source3/wscript
@@ -174,6 +174,20 @@ main() {
     conf.CHECK_STRUCTURE_MEMBER('struct stat', 'st_flags', define='HAVE_STAT_ST_FLAGS',
                                 headers='sys/types.h sys/stat.h unistd.h')
 
+    if "HAVE_BLKCNT_T" in conf.env:
+	conf.CHECK_CODE('''
+	return sizeof(blkcnt_t) == 4 ? 0 : 1''',
+		'SIZEOF_BLKCNT_T_4', execute=True,
+		headers='sys/types.h sys/stat.h unistd.h',
+		msg="Checking whether blkcnt_t is 32 bit")
+
+    if "HAVE_BLKCNT_T" in conf.env:
+	conf.CHECK_CODE('''
+	return sizeof(blkcnt_t) == 8 ? 0 : 1''',
+		'SIZEOF_BLKCNT_T_8', execute=True,
+		headers='sys/types.h sys/stat.h unistd.h',
+		msg="Checking whether blkcnt_t is 64 bit")
+
     # Check for POSIX capability support
     conf.CHECK_FUNCS_IN('cap_get_proc', 'cap', headers='sys/capability.h')