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authorVolker Lendecke <vl@samba.org>2009-02-14 18:01:20 +0100
committerGünther Deschner <gd@samba.org>2009-02-17 10:20:55 +0100
commitea192f08e609fa4c4a48df1b27874b9ae2c1fa40 (patch)
treef15277612eaf3157cc37ff0fa0dc635966b2195b
parent612c5e746bd4d0059eb8bcb8dbb4944db155f071 (diff)
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Fix an invalid typecasting
entry->num_of_strings is a uint16_t. Casting it with (int *)&entry->num_of_strings is wrong, because it gives add_string_to_array the illusion that the object "num" points to is an int, which it is not. In case we are running on a machine where "int" is 32 or 64 bits long, what happens with that cast? "add_string_to_array" interprets the byte field that starts where "num_of_strings" starts as an int. Under very particular circumstances this might work in a limited number of cases: When the byte order of an int is such that the lower order bits of the int are stored first, the subsequent bytes which do not belong to the uint16_t anymore happen to be 0 and the result of the increment still fits into the first 2 bytes of that int, i.e. the result is < 65536. The correct solution to this problem is to use the implicit type conversion that happens when an assignment is done. BTW, this bug is found if you compile with -O3 -Wall, it shows up as a warning: rpc_server/srv_eventlog_lib.c:574: warning: dereferencing type-punned pointer will break strict-aliasing rules Thanks, Volker
-rw-r--r--source3/rpc_server/srv_eventlog_lib.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/source3/rpc_server/srv_eventlog_lib.c b/source3/rpc_server/srv_eventlog_lib.c
index d8c5c3d453..edd1cfacb8 100644
--- a/source3/rpc_server/srv_eventlog_lib.c
+++ b/source3/rpc_server/srv_eventlog_lib.c
@@ -560,6 +560,7 @@ bool parse_logentry( TALLOC_CTX *mem_ctx, char *line, struct eventlog_Record_tdb
}
} else if ( 0 == strncmp( start, "STR", stop - start ) ) {
size_t tmp_len;
+ int num_of_strings;
/* skip past initial ":" */
stop++;
/* now skip any other leading whitespace */
@@ -570,10 +571,15 @@ bool parse_logentry( TALLOC_CTX *mem_ctx, char *line, struct eventlog_Record_tdb
if (tmp_len == (size_t)-1) {
return false;
}
+ num_of_strings = entry->num_of_strings;
if (!add_string_to_array(mem_ctx, stop, &entry->strings,
- (int *)&entry->num_of_strings)) {
+ &num_of_strings)) {
return false;
}
+ if (num_of_strings > 0xffff) {
+ return false;
+ }
+ entry->num_of_strings = num_of_strings;
entry->strings_len += tmp_len;
} else if ( 0 == strncmp( start, "DAT", stop - start ) ) {
/* skip past initial ":" */