staging: erofs: compressed_pages should not be accessed again after freed
This patch resolves the following page use-after-free issue,
z_erofs_vle_unzip:
...
for (i = 0; i < nr_pages; ++i) {
...
z_erofs_onlinepage_endio(page); (1)
}
for (i = 0; i < clusterpages; ++i) {
page = compressed_pages[i];
if (page->mapping == mngda) (2)
continue;
/* recycle all individual staging pages */
(void)z_erofs_gather_if_stagingpage(page_pool, page); (3)
WRITE_ONCE(compressed_pages[i], NULL);
}
...
After (1) is executed, page is freed and could be then reused, if
compressed_pages is scanned after that, it could fall info (2) or
(3) by mistake and that could finally be in a mess.
This patch aims to solve the above issue only with little changes
as much as possible in order to make the fix backport easier.
Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
Cc: <[email protected]> # 4.19+
Signed-off-by: Gao Xiang <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
3 files changed
