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Don't read fields of a misaligned ExpandedObjectHeader or AnyArrayType.

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UBSan complains about this.  Instead, cast to a suitable type requiring
only 4-byte alignment.  DatumGetAnyArrayP() already assumes one can cast
between AnyArrayType and ArrayType, so this doesn't introduce a new
assumption.  Back-patch to 9.5, where AnyArrayType was introduced.

Reviewed by Tom Lane.

Discussion: https://postgr.es/m/20190629210334.GA1244217@rfd.leadboat.com
This commit is contained in:
Noah Misch 2019-06-30 17:34:17 -07:00
parent a1637caee9
commit cd9d48969d
4 changed files with 17 additions and 10 deletions
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2
src/backend/utils/adt/arrayfuncs.c
View File

@ -4108,7 +4108,7 @@ array_contain_compare(AnyArrayType *array1, AnyArrayType *array2, Oid collation,
nelems2 = array2->xpn.nelems;
}
else
deconstruct_array(&(array2->flt),
deconstruct_array((ArrayType *) array2,
element_type, typlen, typbyval, typalign,
&values2, &nulls2, &nelems2);

19
src/include/utils/array.h
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@ -153,7 +153,10 @@ typedef struct ExpandedArrayHeader
/*
* Functions that can handle either a "flat" varlena array or an expanded
* array use this union to work with their input.
* array use this union to work with their input. Don't refer to "flt";
* instead, cast to ArrayType. This struct nominally requires 8-byte
* alignment on 64-bit, but it's often used for an ArrayType having 4-byte
* alignment. UBSan complains about referencing "flt" in such cases.
*/
typedef union AnyArrayType
{
@ -307,17 +310,21 @@ typedef struct ArrayIteratorData *ArrayIterator;
* Macros for working with AnyArrayType inputs. Beware multiple references!
*/
#define AARR_NDIM(a) \
(VARATT_IS_EXPANDED_HEADER(a) ? (a)->xpn.ndims : ARR_NDIM(&(a)->flt))
(VARATT_IS_EXPANDED_HEADER(a) ? \
(a)->xpn.ndims : ARR_NDIM((ArrayType *) (a)))
#define AARR_HASNULL(a) \
(VARATT_IS_EXPANDED_HEADER(a) ? \
((a)->xpn.dvalues != NULL ? (a)->xpn.dnulls != NULL : ARR_HASNULL((a)->xpn.fvalue)) : \
ARR_HASNULL(&(a)->flt))
ARR_HASNULL((ArrayType *) (a)))
#define AARR_ELEMTYPE(a) \
(VARATT_IS_EXPANDED_HEADER(a) ? (a)->xpn.element_type : ARR_ELEMTYPE(&(a)->flt))
(VARATT_IS_EXPANDED_HEADER(a) ? \
(a)->xpn.element_type : ARR_ELEMTYPE((ArrayType *) (a)))
#define AARR_DIMS(a) \
(VARATT_IS_EXPANDED_HEADER(a) ? (a)->xpn.dims : ARR_DIMS(&(a)->flt))
(VARATT_IS_EXPANDED_HEADER(a) ? \
(a)->xpn.dims : ARR_DIMS((ArrayType *) (a)))
#define AARR_LBOUND(a) \
(VARATT_IS_EXPANDED_HEADER(a) ? (a)->xpn.lbound : ARR_LBOUND(&(a)->flt))
(VARATT_IS_EXPANDED_HEADER(a) ? \
(a)->xpn.lbound : ARR_LBOUND((ArrayType *) (a)))
/*

4
src/include/utils/arrayaccess.h
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@ -71,8 +71,8 @@ array_iter_setup(array_iter *it, AnyArrayType *a)
{
it->datumptr = NULL;
it->isnullptr = NULL;
it->dataptr = ARR_DATA_PTR(&a->flt);
it->bitmapptr = ARR_NULLBITMAP(&a->flt);
it->dataptr = ARR_DATA_PTR((ArrayType *) a);
it->bitmapptr = ARR_NULLBITMAP((ArrayType *) a);
}
it->bitmask = 1;
}

2
src/include/utils/expandeddatum.h
View File

@ -126,7 +126,7 @@ struct ExpandedObjectHeader
*/
#define EOH_HEADER_MAGIC (-1)
#define VARATT_IS_EXPANDED_HEADER(PTR) \
(((ExpandedObjectHeader *) (PTR))->vl_len_ == EOH_HEADER_MAGIC)
(((varattrib_4b *) (PTR))->va_4byte.va_header == EOH_HEADER_MAGIC)
/*
* Generic support functions for expanded objects.