From: Tomas Vondra Date: Sat, 16 Nov 2019 01:40:02 +0000 (+0100) Subject: Properly determine length for on-disk TOAST values X-Git-Tag: REL_13_BETA1~1167 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2dc08bd6179d8cf480c93701010c19ad7a9891d8;p=thirdparty%2Fpostgresql.git Properly determine length for on-disk TOAST values In detoast_attr_slice, VARSIZE_ANY was used to compute compressed length of on-disk TOAST values. That's incorrect, because the varlena value may be just a TOAST pointer, producing either bogus value or crashing. This is likely why the code was crashing on big-endian machines before 540f31680913 replaced the VARSIZE with VARSIZE_ANY, which however only masked the issue. Reported-by: Rushabh Lathia Discussion: https://postgr.es/m/CAL-OGkthU9Gs7TZchf5OWaL-Gsi=hXqufTxKv9qpNG73d5na_g@mail.gmail.com --- diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c index f752ac7bbc9..8c89fc2a558 100644 --- a/src/backend/access/common/detoast.c +++ b/src/backend/access/common/detoast.c @@ -233,7 +233,7 @@ detoast_attr_slice(struct varlena *attr, * of a given length (after decompression). */ max_size = pglz_maximum_compressed_size(sliceoffset + slicelength, - TOAST_COMPRESS_SIZE(attr)); + toast_pointer.va_extsize); /* * Fetch enough compressed slices (compressed marker will get set