From 6d88c1fc5f2eba341186e13dc9ab4a0ca8eeeeba Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 7 Jul 2015 18:37:45 +0300 Subject: [PATCH] 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. --- src/interfaces/libpq/fe-protocol2.c | 51 +++++++++++++++++------ src/interfaces/libpq/fe-protocol3.c | 63 ++++++++++++++++++++--------- 2 files changed, 83 insertions(+), 31 deletions(-) diff --git a/src/interfaces/libpq/fe-protocol2.c b/src/interfaces/libpq/fe-protocol2.c index 6eb4590f923..1cd038d8b3c 100644 --- a/src/interfaces/libpq/fe-protocol2.c +++ b/src/interfaces/libpq/fe-protocol2.c @@ -498,10 +498,17 @@ pqParseInput2(PGconn *conn) conn->result = PQmakeEmptyPGresult(conn, PGRES_COMMAND_OK); if (!conn->result) - return; + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + pqSaveErrorResult(conn); + } + } + if (conn->result) + { + strlcpy(conn->result->cmdStatus, conn->workBuffer.data, + CMDSTATUS_LEN); } - strlcpy(conn->result->cmdStatus, conn->workBuffer.data, - CMDSTATUS_LEN); checkXactStatus(conn, conn->workBuffer.data); conn->asyncStatus = PGASYNC_READY; break; @@ -522,8 +529,16 @@ pqParseInput2(PGconn *conn) "unexpected character %c following empty query response (\"I\" message)", id); if (conn->result == NULL) + { conn->result = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY); + if (!conn->result) + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + pqSaveErrorResult(conn); + } + } conn->asyncStatus = PGASYNC_READY; break; case 'K': /* secret key data from the backend */ @@ -965,14 +980,17 @@ pqGetErrorNotice2(PGconn *conn, bool isError) * Make a PGresult to hold the message. We temporarily lie about the * result status, so that PQmakeEmptyPGresult doesn't uselessly copy * conn->errorMessage. + * + * NB: This allocation can fail, if you run out of memory. The rest of the + * function handles that gracefully, and we still try to set the error + * message as the connection's error message. */ res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY); - if (!res) - goto failure; - res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR; - res->errMsg = pqResultStrdup(res, workBuf.data); - if (!res->errMsg) - goto failure; + if (res) + { + res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR; + res->errMsg = pqResultStrdup(res, workBuf.data); + } /* * Break the message into fields. We can't do very much here, but we can @@ -1024,15 +1042,22 @@ pqGetErrorNotice2(PGconn *conn, bool isError) pqClearAsyncResult(conn); conn->result = res; resetPQExpBuffer(&conn->errorMessage); - appendPQExpBufferStr(&conn->errorMessage, res->errMsg); + if (res && !PQExpBufferDataBroken(workBuf) && res->errMsg) + appendPQExpBufferStr(&conn->errorMessage, res->errMsg); + else + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); if (conn->xactStatus == PQTRANS_INTRANS) conn->xactStatus = PQTRANS_INERROR; } else { - if (res->noticeHooks.noticeRec != NULL) - (*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res); - PQclear(res); + if (res) + { + if (res->noticeHooks.noticeRec != NULL) + (*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res); + PQclear(res); + } } termPQExpBuffer(&workBuf); diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c index 99f70c56794..9d48cf7145d 100644 --- a/src/interfaces/libpq/fe-protocol3.c +++ b/src/interfaces/libpq/fe-protocol3.c @@ -204,10 +204,15 @@ pqParseInput3(PGconn *conn) conn->result = PQmakeEmptyPGresult(conn, PGRES_COMMAND_OK); if (!conn->result) - return; + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + pqSaveErrorResult(conn); + } } - strlcpy(conn->result->cmdStatus, conn->workBuffer.data, - CMDSTATUS_LEN); + if (conn->result) + strlcpy(conn->result->cmdStatus, conn->workBuffer.data, + CMDSTATUS_LEN); conn->asyncStatus = PGASYNC_READY; break; case 'E': /* error return */ @@ -226,7 +231,11 @@ pqParseInput3(PGconn *conn) conn->result = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY); if (!conn->result) - return; + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + pqSaveErrorResult(conn); + } } conn->asyncStatus = PGASYNC_READY; break; @@ -239,7 +248,11 @@ pqParseInput3(PGconn *conn) conn->result = PQmakeEmptyPGresult(conn, PGRES_COMMAND_OK); if (!conn->result) - return; + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + pqSaveErrorResult(conn); + } } conn->asyncStatus = PGASYNC_READY; } @@ -306,7 +319,11 @@ pqParseInput3(PGconn *conn) conn->result = PQmakeEmptyPGresult(conn, PGRES_COMMAND_OK); if (!conn->result) - return; + { + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + pqSaveErrorResult(conn); + } } conn->asyncStatus = PGASYNC_READY; } @@ -824,11 +841,14 @@ pqGetErrorNotice3(PGconn *conn, bool isError) * Make a PGresult to hold the accumulated fields. We temporarily lie * about the result status, so that PQmakeEmptyPGresult doesn't uselessly * copy conn->errorMessage. + * + * NB: This allocation can fail, if you run out of memory. The rest of the + * function handles that gracefully, and we still try to set the error + * message as the connection's error message. */ res = PQmakeEmptyPGresult(conn, PGRES_EMPTY_QUERY); - if (!res) - goto fail; - res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR; + if (res) + res->resultStatus = isError ? PGRES_FATAL_ERROR : PGRES_NONFATAL_ERROR; /* * Read the fields and save into res. @@ -945,20 +965,27 @@ pqGetErrorNotice3(PGconn *conn, bool isError) */ if (isError) { - res->errMsg = pqResultStrdup(res, workBuf.data); - if (!res->errMsg) - goto fail; + if (res) + res->errMsg = pqResultStrdup(res, workBuf.data); pqClearAsyncResult(conn); conn->result = res; - appendPQExpBufferStr(&conn->errorMessage, workBuf.data); + if (PQExpBufferDataBroken(workBuf)) + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("out of memory")); + else + appendPQExpBufferStr(&conn->errorMessage, workBuf.data); } else { - /* We can cheat a little here and not copy the message. */ - res->errMsg = workBuf.data; - if (res->noticeHooks.noticeRec != NULL) - (*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res); - PQclear(res); + /* if we couldn't allocate the result set, just discard the NOTICE */ + if (res) + { + /* We can cheat a little here and not copy the message. */ + res->errMsg = workBuf.data; + if (res->noticeHooks.noticeRec != NULL) + (*res->noticeHooks.noticeRec) (res->noticeHooks.noticeRecArg, res); + PQclear(res); + } } termPQExpBuffer(&workBuf);