On Mon, Mar 11, 2019 at 10:29:32AM +0800, Gao Xiang wrote:
commit af692e117cb8cd9d3d844d413095775abc1217f9 upstream.
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: stable@vger.kernel.org # 4.19+ Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com
drivers/staging/erofs/unzip_vle.c | 38 ++++++++++++++++++----------------- drivers/staging/erofs/unzip_vle.h | 3 +-- drivers/staging/erofs/unzip_vle_lz4.c | 19 ++++++++---------- 3 files changed, 29 insertions(+), 31 deletions(-)
diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c index ca2e8fd78959..ab30d14ded06 100644 --- a/drivers/staging/erofs/unzip_vle.c +++ b/drivers/staging/erofs/unzip_vle.c @@ -1017,11 +1017,10 @@ static int z_erofs_vle_unzip(struct super_block *sb, if (llen > grp->llen) llen = grp->llen;
- err = z_erofs_vle_unzip_fast_percpu(compressed_pages,
clusterpages, pages, llen, work->pageofs,z_erofs_onlinepage_endio);
- err = z_erofs_vle_unzip_fast_percpu(compressed_pages, clusterpages,
pages, llen, work->pageofs);
goto out_percpu;
goto out;if (sparsemem_pages >= nr_pages) goto skip_allocpage; @@ -1042,8 +1041,25 @@ static int z_erofs_vle_unzip(struct super_block *sb, erofs_vunmap(vout, nr_pages); out:
- /* must handle all compressed pages before endding pages */
- for (i = 0; i < clusterpages; ++i) {
page = compressed_pages[i];+#ifdef EROFS_FS_HAS_MANAGED_CACHE
if (page->mapping == MNGD_MAPPING(sbi))continue;+#endif
/* recycle all individual staging pages */(void)z_erofs_gather_if_stagingpage(page_pool, page);WRITE_ONCE(compressed_pages[i], NULL);- }
- for (i = 0; i < nr_pages; ++i) { page = pages[i];
if (!page)continue;- DBG_BUGON(!page->mapping);
/* recycle all individual staging pages */ @@ -1056,20 +1072,6 @@ static int z_erofs_vle_unzip(struct super_block *sb, z_erofs_onlinepage_endio(page); } -out_percpu:
- for (i = 0; i < clusterpages; ++i) {
page = compressed_pages[i];-#ifdef EROFS_FS_HAS_MANAGED_CACHE
if (page->mapping == MNGD_MAPPING(sbi))continue;-#endif
/* recycle all individual staging pages */(void)z_erofs_gather_if_stagingpage(page_pool, page);WRITE_ONCE(compressed_pages[i], NULL);- }
- if (pages == z_pagemap_global) mutex_unlock(&z_pagemap_global_lock); else if (unlikely(pages != pages_onstack))
diff --git a/drivers/staging/erofs/unzip_vle.h b/drivers/staging/erofs/unzip_vle.h index 5a4e1b62c0d1..c0dfd6906aa8 100644 --- a/drivers/staging/erofs/unzip_vle.h +++ b/drivers/staging/erofs/unzip_vle.h @@ -218,8 +218,7 @@ extern int z_erofs_vle_plain_copy(struct page **compressed_pages, extern int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages, unsigned clusterpages, struct page **pages,
- unsigned outlen, unsigned short pageofs,
- void (*endio)(struct page *));
- unsigned int outlen, unsigned short pageofs);
extern int z_erofs_vle_unzip_vmap(struct page **compressed_pages, unsigned clusterpages, void *vaddr, unsigned llen, diff --git a/drivers/staging/erofs/unzip_vle_lz4.c b/drivers/staging/erofs/unzip_vle_lz4.c index 52797bd89da1..f471b894c848 100644 --- a/drivers/staging/erofs/unzip_vle_lz4.c +++ b/drivers/staging/erofs/unzip_vle_lz4.c @@ -125,8 +125,7 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages, unsigned int clusterpages, struct page **pages, unsigned int outlen,
unsigned short pageofs,void (*endio)(struct page *))
unsigned short pageofs){ void *vin, *vout; unsigned int nr_pages, i, j; @@ -148,19 +147,16 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages, ret = z_erofs_unzip_lz4(vin, vout + pageofs, clusterpages * PAGE_SIZE, outlen);
- if (ret >= 0) {
outlen = ret;ret = 0;- }
- if (ret < 0)
goto out;- ret = 0;
for (i = 0; i < nr_pages; ++i) { j = min((unsigned int)PAGE_SIZE - pageofs, outlen); if (pages[i]) {
if (ret < 0) {SetPageError(pages[i]);} else if (clusterpages == 1 &&pages[i] == compressed_pages[0]) {
if (clusterpages == 1 &&pages[i] == compressed_pages[0]) { memcpy(vin + pageofs, vout + pageofs, j); } else { void *dst = kmap_atomic(pages[i]);@@ -168,12 +164,13 @@ int z_erofs_vle_unzip_fast_percpu(struct page **compressed_pages, memcpy(dst + pageofs, vout + pageofs, j); kunmap_atomic(dst); }
endio(pages[i]);
+out: preempt_enable(); if (clusterpages == 1) -- 2.14.5
Now applied, thanks.
greg k-h