postgres.git / summary / log / commit / refs

commit    d0519e9fea96331fbc5f6d65373b2411526cd95d
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Thu Jul 23 21:19:37 2020 +0000
First released in: 14.0, 9.5.23, 9.6.19, 10.14, 11.9, 12.4, 13.0

    Fix ancient violation of zlib's API spec.
    
    contrib/pgcrypto mishandled the case where deflate() does not consume
    all of the offered input on the first try.  It reset the next_in pointer
    to the start of the input instead of leaving it alone, causing the wrong
    data to be fed to the next deflate() call.
    
    This has been broken since pgcrypto was committed.  The reason for the
    lack of complaints seems to be that it's fairly hard to get stock zlib
    to not consume all the input, so long as the output buffer is big enough
    (which it normally would be in pgcrypto's usage; AFAICT the input is
    always going to be packetized into packets no larger than ZIP_OUT_BUF).
    However, IBM's zlibNX implementation for AIX evidently will do it
    in some cases.
    
    I did not add a test case for this, because I couldn't find one that
    would fail with stock zlib.  When we put back the test case for
    bug #16476, that will cover the zlibNX situation well enough.
    
    While here, write deflate()'s second argument as Z_NO_FLUSH per its
    API spec, instead of hard-wiring the value zero.
    
    Per buildfarm results and subsequent investigation.
    
    Discussion: https://postgr.es/m/16476-692ef7b84e5fb893@postgresql.org


 contrib/pgcrypto/pgp-compress.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/contrib/pgcrypto/pgp-compress.c b/contrib/pgcrypto/pgp-compress.c
index 57efe733386..e153940ba8c 100644
--- a/contrib/pgcrypto/pgp-compress.c
+++ b/contrib/pgcrypto/pgp-compress.c
@@ -115,13 +115,13 @@ compress_process(PushFilter *next, void *priv, const uint8 *data, int len)
 	/*
 	 * process data
 	 */
-	while (len > 0)
+	st->stream.next_in = (void *) data;
+	st->stream.avail_in = len;
+	while (st->stream.avail_in > 0)
 	{
-		st->stream.next_in = (void *) data;
-		st->stream.avail_in = len;
 		st->stream.next_out = st->buf;
 		st->stream.avail_out = st->buf_len;
-		res = deflate(&st->stream, 0);
+		res = deflate(&st->stream, Z_NO_FLUSH);
 		if (res != Z_OK)
 			return PXE_PGP_COMPRESSION_ERROR;
 
@@ -132,7 +132,6 @@ compress_process(PushFilter *next, void *priv, const uint8 *data, int len)
 			if (res < 0)
 				return res;
 		}
-		len = st->stream.avail_in;
 	}
 
 	return 0;
@@ -155,6 +154,7 @@ compress_flush(PushFilter *next, void *priv)
 		zres = deflate(&st->stream, Z_FINISH);
 		if (zres != Z_STREAM_END && zres != Z_OK)
 			return PXE_PGP_COMPRESSION_ERROR;
+
 		n_out = st->buf_len - st->stream.avail_out;
 		if (n_out > 0)
 		{


[parent: 77033aa97af7]