sharpetronics/PostgreSQL
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-05-12 00:01:58 -04:00
Code Issues Projects Releases Wiki Activity

Be more wary of corrupt data in pageinspect's heap_page_items().

Browse Source 
The original intent in heap_page_items() was to return nulls, not
throw an error or crash, if an item was sufficiently corrupt that
we couldn't safely extract data from it.  However, commit d6061f83a
utterly missed that memo, and not only put in an un-length-checked
copy of the tuple's data section, but also managed to break the check
on sane nulls-bitmap length.  Either mistake could possibly lead to
a SIGSEGV crash if the tuple is corrupt.

Bug: #18896
Reported-by: Dmitry Kovalenko <d.kovalenko@postgrespro.ru>
Author: Dmitry Kovalenko <d.kovalenko@postgrespro.ru>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/18896-add267b8e06663e3@postgresql.org
Backpatch-through: 13
This commit is contained in:
Tom Lane 2025-04-19 16:37:42 -04:00
parent 88e947136b
commit d05996340d
1 changed files with 26 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
contrib/pageinspect/heapfuncs.c
View File

@ -212,11 +212,8 @@ heap_page_items(PG_FUNCTION_ARGS)
lp_offset + lp_len <= raw_page_size)
{
HeapTupleHeader tuphdr;
bytea *tuple_data_bytea;
int tuple_data_len;
/* Extract information from the tuple header */
tuphdr = (HeapTupleHeader) PageGetItem(page, id);
values[4] = UInt32GetDatum(HeapTupleHeaderGetRawXmin(tuphdr));
@ -228,31 +225,32 @@ heap_page_items(PG_FUNCTION_ARGS)
values[9] = UInt32GetDatum(tuphdr->t_infomask);
values[10] = UInt8GetDatum(tuphdr->t_hoff);
/* Copy raw tuple data into bytea attribute */
tuple_data_len = lp_len - tuphdr->t_hoff;
tuple_data_bytea = (bytea *) palloc(tuple_data_len + VARHDRSZ);
SET_VARSIZE(tuple_data_bytea, tuple_data_len + VARHDRSZ);
memcpy(VARDATA(tuple_data_bytea), (char *) tuphdr + tuphdr->t_hoff,
tuple_data_len);
values[13] = PointerGetDatum(tuple_data_bytea);
/*
* We already checked that the item is completely within the raw
* page passed to us, with the length given in the line pointer.
* Let's check that t_hoff doesn't point over lp_len, before using
* it to access t_bits and oid.
* But t_hoff could be out of range, so check it before relying on
* it to fetch additional info.
*/
if (tuphdr->t_hoff >= SizeofHeapTupleHeader &&
tuphdr->t_hoff <= lp_len &&
tuphdr->t_hoff == MAXALIGN(tuphdr->t_hoff))
{
int tuple_data_len;
bytea *tuple_data_bytea;
/* Copy null bitmask and OID, if present */
if (tuphdr->t_infomask & HEAP_HASNULL)
{
int bits_len;
int bitmaplen;
bits_len =
BITMAPLEN(HeapTupleHeaderGetNatts(tuphdr)) * BITS_PER_BYTE;
values[11] = CStringGetTextDatum(bits_to_text(tuphdr->t_bits, bits_len));
bitmaplen = BITMAPLEN(HeapTupleHeaderGetNatts(tuphdr));
/* better range-check the attribute count, too */
if (bitmaplen <= tuphdr->t_hoff - SizeofHeapTupleHeader)
values[11] =
CStringGetTextDatum(bits_to_text(tuphdr->t_bits,
bitmaplen * BITS_PER_BYTE));
else
nulls[11] = true;
}
else
nulls[11] = true;
@ -261,11 +259,22 @@ heap_page_items(PG_FUNCTION_ARGS)
values[12] = HeapTupleHeaderGetOidOld(tuphdr);
else
nulls[12] = true;
/* Copy raw tuple data into bytea attribute */
tuple_data_len = lp_len - tuphdr->t_hoff;
tuple_data_bytea = (bytea *) palloc(tuple_data_len + VARHDRSZ);
SET_VARSIZE(tuple_data_bytea, tuple_data_len + VARHDRSZ);
if (tuple_data_len > 0)
memcpy(VARDATA(tuple_data_bytea),
(char *) tuphdr + tuphdr->t_hoff,
tuple_data_len);
values[13] = PointerGetDatum(tuple_data_bytea);
}
else
{
nulls[11] = true;
nulls[12] = true;
nulls[13] = true;
}
}
else