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authorGao Xiang <gaoxiang25@huawei.com>2020-02-26 16:10:07 +0800
committerGao Xiang <gaoxiang25@huawei.com>2020-03-03 23:40:16 +0800
commitaf1038abbd1449b7feb2b5b7cdbb24aa0bd1f120 (patch)
tree93d226492e5b74c34426d918da01c59d13fd8b43 /fs/erofs
parent9d5a09c6f3b5fb85af20e3a34827b5d27d152b34 (diff)
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erofs: use LZ4_decompress_safe() for full decoding
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 potential corrupted images and it might have some speed gain as well although I didn't observe much difference. Note that legacy compressor (< 5.3, no LZ4_0PADDING) could encode extra data in a pcluster, which is excluded as well. Cc: Lasse Collin <lasse.collin@tukaani.org> Fixes: 0ffd71bcc3a0 ("staging: erofs: introduce LZ4 decompression inplace") [ Gao Xiang: v5.3+, I will manually backport this to stable later. ] Link: https://lore.kernel.org/r/20200226081008.86348-2-gaoxiang25@huawei.com Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Diffstat (limited to 'fs/erofs')
-rw-r--r--fs/erofs/decompressor.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 5779a15c2cd6..cd978af6bdb9 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -157,9 +157,15 @@ 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);
+ /* legacy format could compress extra data in a pcluster. */
+ if (rq->partial_decoding || !support_0padding)
+ 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);