diff options
| author | Gao Xiang <hsiangkao@linux.alibaba.com> | 2025-10-31 13:47:39 +0800 |
|---|---|---|
| committer | Gao Xiang <hsiangkao@linux.alibaba.com> | 2025-11-07 04:10:45 +0800 |
| commit | f2a12cc3b97f062186568a7b94ddb7aa2ef68140 (patch) | |
| tree | dbbef8e9a6ff90f7057fa00ea089a40164ea8277 | |
| parent | 083d7af3350e04c428256a3bd10003f63151b6b1 (diff) | |
erofs: avoid infinite loop due to incomplete zstd-compressed data
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 <rtm@csail.mit.edu>
Closes: https://lore.kernel.org/r/50958.1761605413@localhost
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chunhai Guo <guochunhai@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
| -rw-r--r-- | fs/erofs/decompressor_zstd.c | 11 |
1 files 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); |