Skip to content

Commit 414bef3

Browse files
hlinnakahlinnaka
committed
Improve handling of out-of-memory in libpq.
If an allocation fails in the main message handling loop, pqParseInput3 or pqParseInput2, it should not be treated as "not enough data available yet". Otherwise libpq will wait indefinitely for more data to arrive from the server, and gets stuck forever. This isn't a complete fix - getParamDescriptions and getCopyStart still have the same issue, but it's a step in the right direction. Michael Paquier and me. Backpatch to all supported versions.
1 parent c81c956 commit 414bef3

File tree

2 files changed

+83
-31
lines changed

2 files changed

+83
-31
lines changed

‎src/interfaces/libpq/fe-protocol2.c‎

Lines changed: 38 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -498,10 +498,17 @@ pqParseInput2(PGconn *conn)
498498
conn->result = PQmakeEmptyPGresult(conn,
499499
PGRES_COMMAND_OK);
500500
if (!conn->result)
501-
return;
501+
{
502+
printfPQExpBuffer(&conn->errorMessage,
503+
libpq_gettext("out of memory"));
504+
pqSaveErrorResult(conn);
505+
}
506+
}
507+
if (conn->result)
508+
{
509+
strlcpy(conn->result->cmdStatus, conn->workBuffer.data,
510+
CMDSTATUS_LEN);
502511
}
503-
strlcpy(conn->result->cmdStatus, conn->workBuffer.data,
504-
CMDSTATUS_LEN);
505512
checkXactStatus(conn, conn->workBuffer.data);
506513
conn->asyncStatus = PGASYNC_READY;
507514
break;
@@ -522,8 +529,16 @@ pqParseInput2(PGconn *conn)
522529
"unexpected character %c following empty query response (\"I\" message)",
523530
id);
524531
if (conn->result == NULL)
532+
{
525533
conn->result = PQmakeEmptyPGresult(conn,
526534
PGRES_EMPTY_QUERY);
535+
if (!conn->result)
536+
{
537+
printfPQExpBuffer(&conn->errorMessage,
538+
libpq_gettext("out of memory"));
539+
pqSaveErrorResult(conn);
540+
}
541+
}
527542
conn->asyncStatus = PGASYNC_READY;
528543
break;
529544
case 'K': /* secret key data from the backend */
@@ -965,14 +980,17 @@ pqGetErrorNotice2(PGconn *conn, bool isError)
965980
* Make a PGresult to hold the message. We temporarily lie about the
966981
* result status, so that PQmakeEmptyPGresult doesn't uselessly copy
967982
* conn->errorMessage.
983+
*
984+
* NB: This allocation can fail, if you run out of memory. The rest of the
985+
* function handles that gracefully, and we still try to set the error
986+
* message as the connection's error message.
968987
*/
969988
res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY);
970-
if (!res)
971-
goto failure;
972-
res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR;
973-
res->errMsg = pqResultStrdup(res, workBuf.data);
974-
if (!res->errMsg)
975-
goto failure;
989+
if (res)
990+
{
991+
res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR;
992+
res->errMsg = pqResultStrdup(res, workBuf.data);
993+
}
976994

977995
/*
978996
* Break the message into fields. We can't do very much here, but we can
@@ -1024,15 +1042,22 @@ pqGetErrorNotice2(PGconn *conn, bool isError)
10241042
pqClearAsyncResult(conn);
10251043
conn->result = res;
10261044
resetPQExpBuffer(&conn->errorMessage);
1027-
appendPQExpBufferStr(&conn->errorMessage, res->errMsg);
1045+
if (res && !PQExpBufferDataBroken(workBuf) && res->errMsg)
1046+
appendPQExpBufferStr(&conn->errorMessage, res->errMsg);
1047+
else
1048+
printfPQExpBuffer(&conn->errorMessage,
1049+
libpq_gettext("out of memory"));
10281050
if (conn->xactStatus == PQTRANS_INTRANS)
10291051
conn->xactStatus = PQTRANS_INERROR;
10301052
}
10311053
else
10321054
{
1033-
if (res->noticeHooks.noticeRec != NULL)
1034-
(*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res);
1035-
PQclear(res);
1055+
if (res)
1056+
{
1057+
if (res->noticeHooks.noticeRec != NULL)
1058+
(*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res);
1059+
PQclear(res);
1060+
}
10361061
}
10371062

10381063
termPQExpBuffer(&workBuf);

‎src/interfaces/libpq/fe-protocol3.c‎

Lines changed: 45 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -204,10 +204,15 @@ pqParseInput3(PGconn *conn)
204204
conn->result = PQmakeEmptyPGresult(conn,
205205
PGRES_COMMAND_OK);
206206
if (!conn->result)
207-
return;
207+
{
208+
printfPQExpBuffer(&conn->errorMessage,
209+
libpq_gettext("out of memory"));
210+
pqSaveErrorResult(conn);
211+
}
208212
}
209-
strlcpy(conn->result->cmdStatus, conn->workBuffer.data,
210-
CMDSTATUS_LEN);
213+
if (conn->result)
214+
strlcpy(conn->result->cmdStatus, conn->workBuffer.data,
215+
CMDSTATUS_LEN);
211216
conn->asyncStatus = PGASYNC_READY;
212217
break;
213218
case 'E': /* error return */
@@ -226,7 +231,11 @@ pqParseInput3(PGconn *conn)
226231
conn->result = PQmakeEmptyPGresult(conn,
227232
PGRES_EMPTY_QUERY);
228233
if (!conn->result)
229-
return;
234+
{
235+
printfPQExpBuffer(&conn->errorMessage,
236+
libpq_gettext("out of memory"));
237+
pqSaveErrorResult(conn);
238+
}
230239
}
231240
conn->asyncStatus = PGASYNC_READY;
232241
break;
@@ -239,7 +248,11 @@ pqParseInput3(PGconn *conn)
239248
conn->result = PQmakeEmptyPGresult(conn,
240249
PGRES_COMMAND_OK);
241250
if (!conn->result)
242-
return;
251+
{
252+
printfPQExpBuffer(&conn->errorMessage,
253+
libpq_gettext("out of memory"));
254+
pqSaveErrorResult(conn);
255+
}
243256
}
244257
conn->asyncStatus = PGASYNC_READY;
245258
}
@@ -306,7 +319,11 @@ pqParseInput3(PGconn *conn)
306319
conn->result = PQmakeEmptyPGresult(conn,
307320
PGRES_COMMAND_OK);
308321
if (!conn->result)
309-
return;
322+
{
323+
printfPQExpBuffer(&conn->errorMessage,
324+
libpq_gettext("out of memory"));
325+
pqSaveErrorResult(conn);
326+
}
310327
}
311328
conn->asyncStatus = PGASYNC_READY;
312329
}
@@ -822,11 +839,14 @@ pqGetErrorNotice3(PGconn *conn, bool isError)
822839
* Make a PGresult to hold the accumulated fields. We temporarily lie
823840
* about the result status, so that PQmakeEmptyPGresult doesn't uselessly
824841
* copy conn->errorMessage.
842+
*
843+
* NB: This allocation can fail, if you run out of memory. The rest of the
844+
* function handles that gracefully, and we still try to set the error
845+
* message as the connection's error message.
825846
*/
826847
res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY);
827-
if (!res)
828-
goto fail;
829-
res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR;
848+
if (res)
849+
res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR;
830850

831851
/*
832852
* Read the fields and save into res.
@@ -966,20 +986,27 @@ pqGetErrorNotice3(PGconn *conn, bool isError)
966986
*/
967987
if (isError)
968988
{
969-
res->errMsg = pqResultStrdup(res, workBuf.data);
970-
if (!res->errMsg)
971-
goto fail;
989+
if (res)
990+
res->errMsg = pqResultStrdup(res, workBuf.data);
972991
pqClearAsyncResult(conn);
973992
conn->result = res;
974-
appendPQExpBufferStr(&conn->errorMessage, workBuf.data);
993+
if (PQExpBufferDataBroken(workBuf))
994+
printfPQExpBuffer(&conn->errorMessage,
995+
libpq_gettext("out of memory"));
996+
else
997+
appendPQExpBufferStr(&conn->errorMessage, workBuf.data);
975998
}
976999
else
9771000
{
978-
/* We can cheat a little here and not copy the message. */
979-
res->errMsg = workBuf.data;
980-
if (res->noticeHooks.noticeRec != NULL)
981-
(*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res);
982-
PQclear(res);
1001+
/* if we couldn't allocate the result set, just discard the NOTICE */
1002+
if (res)
1003+
{
1004+
/* We can cheat a little here and not copy the message. */
1005+
res->errMsg = workBuf.data;
1006+
if (res->noticeHooks.noticeRec != NULL)
1007+
(*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res);
1008+
PQclear(res);
1009+
}
9831010
}
9841011

9851012
termPQExpBuffer(&workBuf);

0 commit comments

Comments
 (0)