From c6289309669e5b3892816e0719afbce797598f54 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 6 Jan 2006 02:58:32 +0000 Subject: [PATCH] Fix Windows-only postmaster code to reject a connection request and continue, rather than elog(FATAL), when there is no more room in ShmemBackendArray. This is a security issue since too many connection requests arriving close together could cause the postmaster to shut down, resulting in denial of service. Reported by Yoshiyuki Asaba, fixed by Magnus Hagander. --- src/backend/postmaster/postmaster.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index b691e0c4eff..518aabd4bf8 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -37,7 +37,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.475.2.1 2005/11/22 18:23:15 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.475.2.2 2006/01/06 02:58:32 tgl Exp $ * * NOTES * @@ -147,7 +147,11 @@ typedef struct bkend static Dllist *BackendList; #ifdef EXEC_BACKEND -#define NUM_BACKENDARRAY_ELEMS (2*MaxBackends) +/* + * Number of entries in the backend table. Twice the number of backends, + * plus four other subprocesses (stats, bgwriter, autovac, logger). + */ +#define NUM_BACKENDARRAY_ELEMS (2*MaxBackends + 4) static Backend *ShmemBackendArray; #endif @@ -3019,6 +3023,15 @@ internal_forkexec(int argc, char *argv[], Port *port) Assert(strncmp(argv[1], "-fork", 5) == 0); Assert(argv[2] == NULL); + /* Verify that there is room in the child list */ + if (win32_numChildren >= NUM_BACKENDARRAY_ELEMS) + { + elog(LOG, "no room for child entry in backend list"); + /* Report same error as for a fork failure on Unix */ + errno = EAGAIN; + return -1; + } + /* Set up shared memory for parameter passing */ ZeroMemory(&sa, sizeof(sa)); sa.nLength = sizeof(sa);