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f2fs: fix leaking uninitialized memory in compressed clusters 

When the compressed data of a cluster doesn't end on a page boundary,
the remainder of the last page must be zeroed in order to avoid leaking
uninitialized memory to disk.

Fixes: 4c8ff7095b ("f2fs: support data compression")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Eric Biggers 2020-02-20 20:50:37 -08:00 committed by Jaegeuk Kim
parent bf22c3cc8c
commit 7fa6d59816
1 changed files with 6 additions and 2 deletions
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8
fs/f2fs/compress.c
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@ -385,11 +385,15 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
for (i = 0; i < COMPRESS_DATA_RESERVED_SIZE; i++)
cc->cbuf->reserved[i] = cpu_to_le32(0);
nr_cpages = DIV_ROUND_UP(cc->clen + COMPRESS_HEADER_SIZE, PAGE_SIZE);
/* zero out any unused part of the last page */
memset(&cc->cbuf->cdata[cc->clen], 0,
(nr_cpages * PAGE_SIZE) - (cc->clen + COMPRESS_HEADER_SIZE));
vunmap(cc->cbuf);
vunmap(cc->rbuf);
nr_cpages = DIV_ROUND_UP(cc->clen + COMPRESS_HEADER_SIZE, PAGE_SIZE);
for (i = nr_cpages; i < cc->nr_cpages; i++) {
f2fs_put_compressed_page(cc->cpages[i]);
cc->cpages[i] = NULL;