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Commit e0cb828

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michaelpqmichaelpq
committed
Fix corner case with PGP decompression in pgcrypto
A compressed stream may end with an empty packet, and PGP decompression finished before reading this empty packet in the remaining stream. This caused a failure in pgcrypto, handling this case as corrupted data. This commit makes sure to consume such extra data, avoiding a failure when decompression the entire stream. This corner case was reproducible with a data length of 16kB, and existed since its introduction in e94dd6a. A cheap regression test is added to cover this case. Thanks to Jeff Janes for the extra investigation. Reported-by: Frank Gagnepain Author: Kyotaro Horiguchi, Michael Paquier Discussion: https://postgr.es/m/16476-692ef7b84e5fb893@postgresql.org Backpatch-through: 9.5
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‎contrib/pgcrypto/expected/pgp-compression.out

Copy file name to clipboardExpand all lines: contrib/pgcrypto/expected/pgp-compression.out
+30Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -48,3 +48,33 @@ select pgp_sym_decrypt(
4848
Secret message
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(1 row)
5050

51+
-- check corner case involving an input string of 16kB, as per bug #16476.
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SELECT setseed(0);
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setseed
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---------
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(1 row)
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WITH random_string AS
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(
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-- This generates a random string of 16366 bytes. This is chosen
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-- as random so that it does not get compressed, and the decompression
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-- would work on a string with the same length as the origin, making the
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-- test behavior more predictible. lpad() ensures that the generated
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-- hexadecimal value is completed by extra zero characters if random()
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-- has generated a value strictly lower than 16.
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SELECT string_agg(decode(lpad(to_hex((random()*256)::int), 2, '0'), 'hex'), '') as bytes
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FROM generate_series(0, 16365)
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)
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SELECT bytes =
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pgp_sym_decrypt_bytea(
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pgp_sym_encrypt_bytea(bytes, 'key',
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'compress-algo=1,compress-level=1'),
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'key', 'expect-compress-algo=1')
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AS is_same
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FROM random_string;
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is_same
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---------
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t
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(1 row)
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‎contrib/pgcrypto/pgp-compress.c

Copy file name to clipboardExpand all lines: contrib/pgcrypto/pgp-compress.c
+11-11Lines changed: 11 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -244,6 +244,17 @@ decompress_read(void *priv, PullFilter *src, int len,
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struct DecomprData *dec = priv;
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restart:
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if (dec->stream.avail_in == 0)
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{
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uint8 *tmp;
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res = pullf_read(src, 8192, &tmp);
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if (res < 0)
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return res;
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dec->stream.next_in = tmp;
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dec->stream.avail_in = res;
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}
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if (dec->buf_data > 0)
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{
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if (len > dec->buf_data)
@@ -257,17 +268,6 @@ decompress_read(void *priv, PullFilter *src, int len,
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if (dec->eof)
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return 0;
259270

260-
if (dec->stream.avail_in == 0)
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{
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uint8 *tmp;
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res = pullf_read(src, 8192, &tmp);
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if (res < 0)
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return res;
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dec->stream.next_in = tmp;
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dec->stream.avail_in = res;
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}
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dec->stream.next_out = dec->buf;
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dec->stream.avail_out = dec->buf_len;
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dec->pos = dec->buf;

‎contrib/pgcrypto/sql/pgp-compression.sql

Copy file name to clipboardExpand all lines: contrib/pgcrypto/sql/pgp-compression.sql
+21Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -28,3 +28,24 @@ select pgp_sym_decrypt(
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pgp_sym_encrypt('Secret message', 'key',
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'compress-algo=2, compress-level=0'),
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'key', 'expect-compress-algo=0');
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-- check corner case involving an input string of 16kB, as per bug #16476.
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SELECT setseed(0);
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WITH random_string AS
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(
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-- This generates a random string of 16366 bytes. This is chosen
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-- as random so that it does not get compressed, and the decompression
38+
-- would work on a string with the same length as the origin, making the
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-- test behavior more predictible. lpad() ensures that the generated
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-- hexadecimal value is completed by extra zero characters if random()
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-- has generated a value strictly lower than 16.
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SELECT string_agg(decode(lpad(to_hex((random()*256)::int), 2, '0'), 'hex'), '') as bytes
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FROM generate_series(0, 16365)
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)
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SELECT bytes =
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pgp_sym_decrypt_bytea(
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pgp_sym_encrypt_bytea(bytes, 'key',
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'compress-algo=1,compress-level=1'),
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'key', 'expect-compress-algo=1')
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AS is_same
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FROM random_string;

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