Currently, the decompression logic incorrectly spins if compressed
data is truncated in crafted (deliberately corrupted) images.
Fixes: 7c35de4df105 ("erofs: Zstandard compression support")
Reported-by: Robert Morris <[email protected]>
Closes: https://lore.kernel.org/r/50958.1761605413@localhost
Signed-off-by: Gao Xiang <[email protected]>
---
Actually I suspect multi-shot decompressor lzma may have a similar
issue (but it seems deflate is not), will check later.
fs/erofs/decompressor_zstd.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/fs/erofs/decompressor_zstd.c b/fs/erofs/decompressor_zstd.c
index b4bfe14229f9..e38d93bb2104 100644
--- a/fs/erofs/decompressor_zstd.c
+++ b/fs/erofs/decompressor_zstd.c
@@ -172,7 +172,6 @@ static int z_erofs_zstd_decompress(struct
z_erofs_decompress_req *rq,
dctx.bounce = strm->bounce;
do {
- dctx.avail_out = out_buf.size - out_buf.pos;
dctx.inbuf_sz = in_buf.size;
dctx.inbuf_pos = in_buf.pos;
err = z_erofs_stream_switch_bufs(&dctx, &out_buf.dst,
@@ -188,14 +187,18 @@ static int z_erofs_zstd_decompress(struct
z_erofs_decompress_req *rq,
in_buf.pos = dctx.inbuf_pos;
zerr = zstd_decompress_stream(stream, &out_buf, &in_buf);
- if (zstd_is_error(zerr) || (!zerr && rq->outputsize)) {
+ dctx.avail_out = out_buf.size - out_buf.pos;
+ if (zstd_is_error(zerr) ||
+ ((rq->outputsize + dctx.avail_out) && (!zerr || (zerr > 0 &&
+ !(rq->inputsize + in_buf.size - in_buf.pos)))))
{
erofs_err(sb, "failed to decompress in[%u] out[%u]: %s",
rq->inputsize, rq->outputsize,
- zerr ? zstd_get_error_name(zerr) :
"unexpected end of stream");
+ zstd_is_error(zerr) ?
zstd_get_error_name(zerr) :
+ "unexpected end of stream");
err = -EFSCORRUPTED;
break;
}
- } while (rq->outputsize || out_buf.pos < out_buf.size);
+ } while (rq->outputsize + dctx.avail_out);
if (dctx.kout)
kunmap_local(dctx.kout);
--
2.43.5
