From c5269472ea9bb4a6fbb8a0510f7d676d725933ab Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 8 Nov 2017 16:50:12 -0500 Subject: [PATCH] Fix two violations of the ResourceOwnerEnlarge/Remember protocol. The point of having separate ResourceOwnerEnlargeFoo and ResourceOwnerRememberFoo functions is so that resource allocation can happen in between. Doing it in some other order is just wrong. OpenTemporaryFile() did open(), enlarge, remember, which would leak the open file if the enlarge step ran out of memory. Because fd.c has its own layer of resource-remembering, the consequences look like they'd be limited to an intratransaction FD leak, but it's still not good. IncrBufferRefCount() did enlarge, remember, incr-refcount, which would blow up if the incr-refcount step ever failed. It was safe enough when written, but since the introduction of PrivateRefCountHash, I think the assumption that no error could happen there is pretty shaky. The odds of real problems from either bug are probably small, but still, back-patch to supported branches. Thomas Munro and Tom Lane, per a comment from Andres Freund --- src/backend/storage/buffer/bufmgr.c | 2 +- src/backend/storage/file/fd.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 572f413d6e..26df7cb38f 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -3348,7 +3348,6 @@ IncrBufferRefCount(Buffer buffer) { Assert(BufferIsPinned(buffer)); ResourceOwnerEnlargeBuffers(CurrentResourceOwner); - ResourceOwnerRememberBuffer(CurrentResourceOwner, buffer); if (BufferIsLocal(buffer)) LocalRefCount[-buffer - 1]++; else @@ -3359,6 +3358,7 @@ IncrBufferRefCount(Buffer buffer) Assert(ref != NULL); ref->refcount++; } + ResourceOwnerRememberBuffer(CurrentResourceOwner, buffer); } /* diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c index 3849bfb15d..aa2fe2c6c0 100644 --- a/src/backend/storage/file/fd.c +++ b/src/backend/storage/file/fd.c @@ -1397,6 +1397,13 @@ OpenTemporaryFile(bool interXact) { File file = 0; + /* + * Make sure the current resource owner has space for this File before we + * open it, if we'll be registering it below. + */ + if (!interXact) + ResourceOwnerEnlargeFiles(CurrentResourceOwner); + /* * If some temp tablespace(s) have been given to us, try to use the next * one. If a given tablespace can't be found, we silently fall back to @@ -1433,9 +1440,8 @@ OpenTemporaryFile(bool interXact) { VfdCache[file].fdstate |= FD_XACT_TEMPORARY; - ResourceOwnerEnlargeFiles(CurrentResourceOwner); - ResourceOwnerRememberFile(CurrentResourceOwner, file); VfdCache[file].resowner = CurrentResourceOwner; + ResourceOwnerRememberFile(CurrentResourceOwner, file); /* ensure cleanup happens at eoxact */ have_xact_temporary_files = true;