sin/samba-mirror
1
0
Fork 0
mirror of https://github.com/samba-team/samba.git synced 2025-01-12 09:18:10 +03:00
Code

s3:registry: fix seqnum race in regdb_fetch_keys_internal

Browse Source 
This prevents race between fetching seqnum and key content.

Because there is currently no way to atomically fetch the
record along with the seqnum, I use a loop.
This is far from optimal and should should ideally be done
differently. But for now it fixes the race.

Signed-off-by: Andreas Schneider <asn@samba.org>
This commit is contained in:
Michael Adam 2012-04-11 15:51:40 +02:00 committed by Andreas Schneider
parent 7ea8bd3605
commit 22451f7f45
1 changed files with 22 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
source3/registry/reg_backend_db.c
View File

@ -1712,6 +1712,7 @@ static WERROR regdb_fetch_keys_internal(struct db_context *db, const char *key,
fstring subkeyname;
TALLOC_CTX *frame = talloc_stackframe();
TDB_DATA value;
int seqnum[2], count;
DEBUG(11,("regdb_fetch_keys: Enter key => [%s]\n", key ? key : "NULL"));
@ -1724,10 +1725,28 @@ static WERROR regdb_fetch_keys_internal(struct db_context *db, const char *key,
werr = regsubkey_ctr_reinit(ctr);
W_ERROR_NOT_OK_GOTO_DONE(werr);
werr = regsubkey_ctr_set_seqnum(ctr, dbwrap_get_seqnum(db));
W_ERROR_NOT_OK_GOTO_DONE(werr);
count = 0;
ZERO_STRUCT(value);
seqnum[0] = dbwrap_get_seqnum(db);
value = regdb_fetch_key_internal(db, frame, key);
do {
count++;
TALLOC_FREE(value.dptr);
value = regdb_fetch_key_internal(db, frame, key);
seqnum[count % 2] = dbwrap_get_seqnum(db);
} while (seqnum[0] != seqnum[1]);
if (count > 1) {
DEBUG(5, ("regdb_fetch_keys_internal: it took %d attempts to "
"fetch key '%s' with constant seqnum\n",
count, key));
}
werr = regsubkey_ctr_set_seqnum(ctr, seqnum[0]);
if (!W_ERROR_IS_OK(werr)) {
goto done;
}
if (value.dsize == 0 || value.dptr == NULL) {
DEBUG(10, ("regdb_fetch_keys: no subkeys found for key [%s]\n",