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staging: erofs: detect potential multiref due to corrupted images

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As reported by erofs-utils fuzzer, currently, multiref
(ondisk deduplication) hasn't been supported for now,
we should forbid it properly.

Fixes: 3883a79abd ("staging: erofs: introduce VLE decompression support")
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20190821140152.229648-1-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gao Xiang 2019-08-21 22:01:52 +08:00 committed by Greg Kroah-Hartman
parent 8467c3b456
commit e12a0ce2fa
1 changed files with 17 additions and 3 deletions
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20
drivers/staging/erofs/zdata.c
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@ -798,6 +798,7 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
for (i = 0; i < nr_pages; ++i)
pages[i] = NULL;
err = 0;
z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
cl->pagevec, 0);
@ -819,8 +820,17 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
pagenr = z_erofs_onlinepage_index(page);
DBG_BUGON(pagenr >= nr_pages);
DBG_BUGON(pages[pagenr]);
/*
* currently EROFS doesn't support multiref(dedup),
* so here erroring out one multiref page.
*/
if (unlikely(pages[pagenr])) {
DBG_BUGON(1);
SetPageError(pages[pagenr]);
z_erofs_onlinepage_endio(pages[pagenr]);
err = -EFSCORRUPTED;
}
pages[pagenr] = page;
}
z_erofs_pagevec_ctor_exit(&ctor, true);
@ -828,7 +838,6 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
overlapped = false;
compressed_pages = pcl->compressed_pages;
err = 0;
for (i = 0; i < clusterpages; ++i) {
unsigned int pagenr;
@ -852,7 +861,12 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
pagenr = z_erofs_onlinepage_index(page);
DBG_BUGON(pagenr >= nr_pages);
DBG_BUGON(pages[pagenr]);
if (unlikely(pages[pagenr])) {
DBG_BUGON(1);
SetPageError(pages[pagenr]);
z_erofs_onlinepage_endio(pages[pagenr]);
err = -EFSCORRUPTED;
}
pages[pagenr] = page;
overlapped = true;