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Properly determine length for on-disk TOAST values

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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
540f316809 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
This commit is contained in:
Tomas Vondra 2019-11-16 02:40:02 +01:00
parent d482f7f867
commit 2dc08bd617
1 changed files with 1 additions and 1 deletions
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2
src/backend/access/common/detoast.c
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@ -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