Fix the bounds-checking code.

The code that set the bit within the select bitfield was correct, but the
bounds-checking code was not.  The change to that line uses the new _bitsize
macro for clarity.  Also, FD_ZERO macro did not zero-out anything but the
first word of the bitfield, so this could have caused problems with modules
using that macro with the expanded bitfield.

(closes issue #18773)
 Reported by: jamicque
 Patches:
       20110423__issue18773.diff.txt uploaded by tilghman (license 14)
 Tested by: chris-mac

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@315501 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/include/asterisk/select.h b/include/asterisk/select.h
index 5ba189a1022eef1d904dadd19a0383174d378735..50e5b8befbc328a972f5d2fd9ff40db9277d2da9 100644 (file)
--- a/include/asterisk/select.h
+++ b/include/asterisk/select.h
@@ -42,12 +42,14 @@ typedef struct {
        TYPEOF_FD_SET_FDS_BITS fds_bits[ast_FDMAX / 8 / SIZEOF_FD_SET_FDS_BITS]; /* 32768 bits */
 } ast_fdset;
 
+#define _bitsize(a)    (sizeof(a) * 8)
+
 #undef FD_ZERO
 #define FD_ZERO(a) \
        do { \
                TYPEOF_FD_SET_FDS_BITS *bytes = (TYPEOF_FD_SET_FDS_BITS *) a; \
                int i; \
-               for (i = 0; i < sizeof(*(a)) / SIZEOF_FD_SET_FDS_BITS; i++) { \
+               for (i = 0; i < ast_FDMAX / _bitsize(TYPEOF_FD_SET_FDS_BITS); i++) { \
                        bytes[i] = 0; \
                } \
        } while (0)
@@ -55,10 +57,12 @@ typedef struct {
 #define FD_SET(fd, fds) \
        do { \
                TYPEOF_FD_SET_FDS_BITS *bytes = (TYPEOF_FD_SET_FDS_BITS *) fds; \
-               if (fd / sizeof(*bytes) + ((fd + 1) % sizeof(*bytes) ? 1 : 0) < sizeof(*(fds))) { \
-                       bytes[fd / (sizeof(*bytes) * 8)] |= ((TYPEOF_FD_SET_FDS_BITS) 1) << (fd % (sizeof(*bytes) * 8)); \
+               /* 32bit: FD / 32 + ((FD + 1) % 32 ? 1 : 0) < 1024 */ \
+               /* 64bit: FD / 64 + ((FD + 1) % 64 ? 1 : 0) < 512 */ \
+               if (fd / _bitsize(*bytes) + ((fd + 1) % _bitsize(*bytes) ? 1 : 0) < sizeof(*(fds)) / SIZEOF_FD_SET_FDS_BITS) { \
+                       bytes[fd / _bitsize(*bytes)] |= ((TYPEOF_FD_SET_FDS_BITS) 1) << (fd % _bitsize(*bytes)); \
                } else { \
-                       ast_log(LOG_ERROR, "FD %d exceeds the maximum size of ast_fdset!\n", fd); \
+                       fprintf(stderr, "FD %d exceeds the maximum size of ast_fdset!\n", fd); \
                } \
        } while (0)
 #endif /* HAVE_VARIABLE_FDSET */