On 2023/12/29 19:09, Edward Adam Davis wrote:
When LZ4 decompression fails, the number of bytes read from out should be
inputsize plus the returned overflow value ret.

Reported-and-tested-by: [email protected]
Signed-off-by: Edward Adam Davis <[email protected]>
---
  fs/erofs/decompressor.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 021be5feb1bc..8ac3f96676c4 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -250,7 +250,8 @@ static int z_erofs_lz4_decompress_mem(struct 
z_erofs_lz4_decompress_ctx *ctx,
                print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
                               16, 1, src + inputmargin, rq->inputsize, true);
                print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
-                              16, 1, out, rq->outputsize, true);
+                              16, 1, out, (ret < 0 && rq->inputsize > 0) ?
+                              (ret + rq->inputsize) : rq->outputsize, true);

It's incorrect since output decompressed buffer has no relationship
with `rq->inputsize` and `ret + rq->inputsize` is meaningless too.

Also, the issue was already fixed by avoiding debugging messages as
https://lore.kernel.org/r/[email protected]

Thanks,
Gao Xiang

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