Messages in this thread Patch in this message | | | From | Gao Xiang <> | Subject | [PATCH 2/3] erofs: use LZ4_decompress_safe() for full decoding | Date | Wed, 26 Feb 2020 10:30:10 +0800 |
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As Lasse pointed out, "EROFS uses LZ4_decompress_safe_partial for both partial and full blocks. Thus when it is decoding a full block, it doesn't know if the LZ4 decoder actually decoded all the input. The real uncompressed size could be bigger than the value stored in the file system metadata.
Using LZ4_decompress_safe instead of _safe_partial when decompressing a full block would help to detect errors."
So it's reasonable to use _safe in case of corrupted images and it might have some speed gain as well although I didn't observe much difference.
Cc: Lasse Collin <lasse.collin@tukaani.org> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> --- fs/erofs/decompressor.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 5779a15c2cd6..c77cec4327fa 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -157,9 +157,14 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out) } } - ret = LZ4_decompress_safe_partial(src + inputmargin, out, - inlen, rq->outputsize, - rq->outputsize); + if (rq->partial_decoding) + ret = LZ4_decompress_safe_partial(src + inputmargin, out, + inlen, rq->outputsize, + rq->outputsize); + else + ret = LZ4_decompress_safe(src + inputmargin, out, + inlen, rq->outputsize); + if (ret < 0) { erofs_err(rq->sb, "failed to decompress, in[%u, %u] out[%u]", inlen, inputmargin, rq->outputsize); -- 2.17.1
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