From: David Rowley <drowley@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix bogus use of "long" in AllocSetCheck()
Date: Thu, 30 Oct 2025 01:48:43 +0000
Message-ID: <E1vEHmN-004AXV-1M@gemulon.postgresql.org> (raw)
Fix bogus use of "long" in AllocSetCheck()
Because long is 32-bit on 64-bit Windows, it isn't a good datatype to
store the difference between 2 pointers. The under-sized type could
overflow and lead to scary warnings in MEMORY_CONTEXT_CHECKING builds,
such as:
WARNING: problem in alloc set ExecutorState: bad single-chunk %p in block %p
However, the problem lies only in the code running the check, not from
an actual memory accounting bug.
Fix by using "Size" instead of "long". This means using an unsigned
type rather than the previous signed type. If the block's freeptr was
corrupted, we'd still catch that if the unsigned type wrapped. Unsigned
allows us to avoid further needless complexities around comparing signed
and unsigned types.
Author: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Backpatch-through: 13
Discussion: https://postgr.es/m/CAApHDvo-RmiT4s33J=aC9C_-wPZjOXQ232V-EZFgKftSsNRi4w@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/50eb4e11815664bfcee883e92f4bf238ac23ec12
Modified Files
--------------
src/backend/utils/mmgr/aset.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: drowley@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix bogus use of "long" in AllocSetCheck()
In-Reply-To: <E1vEHmN-004AXV-1M@gemulon.postgresql.org>
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