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amcheck: Add additional TOAST pointer checks.

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Expand the checks of toasted attributes to complain if the rawsize is
overlarge.  For compressed attributes, also complain if compression
appears to have expanded the attribute or if the compression method is
invalid.

Mark Dilger, reviewed by Justin Pryzby, Alexander Alekseev, Heikki
Linnakangas, Greg Stark, and me.

Discussion: http://postgr.es/m/8E42250D-586A-4A27-B317-8B062C3816A8@enterprisedb.com
This commit is contained in:
Robert Haas
2021-11-05 09:17:40 -04:00
parent db7d1a7b05
commit bd807be693
2 changed files with 67 additions and 3 deletions
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46
contrib/amcheck/verify_heapam.c
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@ -30,6 +30,9 @@ PG_FUNCTION_INFO_V1(verify_heapam);
/* The number of columns in tuples returned by verify_heapam */
#define HEAPCHECK_RELATION_COLS 4
/* The largest valid toast va_rawsize */
#define VARLENA_SIZE_LIMIT 0x3FFFFFFF
/*
* Despite the name, we use this for reporting problems with both XIDs and
* MXIDs.
@ -1414,6 +1417,49 @@ check_tuple_attribute(HeapCheckContext *ctx)
*/
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
/* Toasted attributes too large to be untoasted should never be stored */
if (toast_pointer.va_rawsize > VARLENA_SIZE_LIMIT)
report_corruption(ctx,
psprintf("toast value %u rawsize %u exceeds limit %u",
toast_pointer.va_valueid,
toast_pointer.va_rawsize,
VARLENA_SIZE_LIMIT));
if (VARATT_IS_COMPRESSED(&toast_pointer))
{
ToastCompressionId cmid;
bool valid = false;
/* Compression should never expand the attribute */
if (VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) > toast_pointer.va_rawsize - VARHDRSZ)
report_corruption(ctx,
psprintf("toast value %u external size %u exceeds maximum expected for rawsize %u",
toast_pointer.va_valueid,
VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer),
toast_pointer.va_rawsize));
/* Compressed attributes should have a valid compression method */
cmid = TOAST_COMPRESS_METHOD(&toast_pointer);
switch (cmid)
{
/* List of all valid compression method IDs */
case TOAST_PGLZ_COMPRESSION_ID:
case TOAST_LZ4_COMPRESSION_ID:
valid = true;
break;
/* Recognized but invalid compression method ID */
case TOAST_INVALID_COMPRESSION_ID:
break;
/* Intentionally no default here */
}
if (!valid)
report_corruption(ctx,
psprintf("toast value %u has invalid compression method id %d",
toast_pointer.va_valueid, cmid));
}
/* The tuple header better claim to contain toasted values */
if (!(infomask & HEAP_HASEXTERNAL))
{