Commit 6d89f743 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Herbert Xu
Browse files

crypto: deflate - fix spurious -ENOSPC 



The code in deflate_decompress_one may erroneously return -ENOSPC even if
it didn't run out of output space. The error happens under this
condition:

- Suppose that there are two input pages, the compressed data fits into
  the first page and the zlib checksum is placed in the second page.

- The code iterates over the first page, decompresses the data and fully
  fills the destination buffer, zlib_inflate returns Z_OK becuse zlib
  hasn't seen the checksum yet.

- The outer do-while loop is iterated again, acomp_walk_next_src sets the
  input parameters to the second page containing the checksum.

- We go into the inner do-while loop, execute "dcur =
  acomp_walk_next_dst(&walk);". "dcur" is zero, so we break out of the
  loop and return -ENOSPC, despite the fact that the decompressed data
  fit into the destination buffer.

In order to fix this bug, this commit changes the logic when to report
the -ENOSPC error. We report the error if the destination buffer is empty
*and* if zlib_inflate didn't make any progress consuming the input
buffer. If zlib_inflate consumes the trailing checksum, we see that it
made progress and we will not return -ENOSPC.

Fixes: 08cabc7d ("crypto: deflate - Convert to acomp")
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 80688afb

crypto/deflate.c

+7 −4
Original line number Diff line number Diff line
@@ -164,18 +164,21 @@ static int deflate_decompress_one(struct acomp_req *req, 


		do {

			unsigned int dcur;

			unsigned long avail_in;



			dcur = acomp_walk_next_dst(&walk);

			if (!dcur) {

				out_of_space = true;

				break;

			}



			stream->avail_out = dcur;

			stream->next_out = walk.dst.virt.addr;

			avail_in = stream->avail_in;



			ret = zlib_inflate(stream, Z_NO_FLUSH);



			if (!dcur && avail_in == stream->avail_in) {

				out_of_space = true;

				break;

			}



			dcur -= stream->avail_out;

			acomp_walk_done_dst(&walk, dcur);

		} while (ret == Z_OK && stream->avail_in);