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Message-ID: <tencent_8D66B23C9D36BA971637084BA27411767F09@qq.com>
From: Edward Adam Davis <eadavis@qq.com>
To: syzbot+6c746eea496f34b3161d@syzkaller.appspotmail.com
Cc: chao@kernel.org,
	huyue2@coolpad.com,
	jefflexu@linux.alibaba.com,
	linux-erofs@lists.ozlabs.org,
	linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com,
	xiang@kernel.org
Subject: [PATCH] erofs: fix uninit-value in z_erofs_lz4_decompress
Date: Fri, 29 Dec 2023 19:09:39 +0800
In-Reply-To: <000000000000321c24060d7cfa1c@google.com>
References: <000000000000321c24060d7cfa1c@google.com>
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When LZ4 decompression fails, the number of bytes read from out should be 
inputsize plus the returned overflow value ret.

Reported-and-tested-by: syzbot+6c746eea496f34b3161d@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 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);
 
 		if (ret >= 0)
 			memset(out + ret, 0, rq->outputsize - ret);
-- 
2.43.0