There could be a potential race between these two paths below,
leading to use-after-free when accessing bio->bi_crypt_context.
f2fs_write_cache_pages
->f2fs_do_write_data_page on page#1
->f2fs_inplace_write_data
->f2fs_merge_page_bio
->add_bio_entry
->f2fs_do_write_data_page on page#2
->f2fs_inplace_write_data
->f2fs_merge_page_bio
->f2fs_crypt_mergeable_bio
->fscrypt_mergeable_bio
f2fs_write_begin on page#1
->f2fs_wait_on_page_writeback
->f2fs_submit_merged_ipu_write
->__submit_bio
The bio gets completed, calling
bio_endio
->bio_uninit
->bio_crypt_free_ctx
->use-after-free issue
Fix this by moving f2fs_crypt_mergeable_bio() check within
add_ipu_page() so that it's done under bio_list_lock to prevent
the above race.
Fixes: 15e76ad23e72 ("f2fs: add inline encryption support")
Signed-off-by: Sahitya Tummala <[email protected]>
---
This fix is rebased to the tip of fscrypt git -
https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git
branch - inline-encryption
fs/f2fs/data.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 0dfa8d3..3b53554 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -762,9 +762,10 @@ static void del_bio_entry(struct bio_entry *be)
kmem_cache_free(bio_entry_slab, be);
}
-static int add_ipu_page(struct f2fs_sb_info *sbi, struct bio **bio,
- struct page *page)
+static int add_ipu_page(struct f2fs_io_info *fio, struct bio **bio,
+ struct page *page, int *bio_needs_submit)
{
+ struct f2fs_sb_info *sbi = fio->sbi;
enum temp_type temp;
bool found = false;
int ret = -EAGAIN;
@@ -780,6 +781,15 @@ static int add_ipu_page(struct f2fs_sb_info *sbi, struct
bio **bio,
continue;
found = true;
+ if (*bio && (!page_is_mergeable(sbi, *bio,
+ *fio->last_block, fio->new_blkaddr) ||
+ !f2fs_crypt_mergeable_bio(*bio,
+ fio->page->mapping->host,
+ fio->page->index, fio))) {
+ ret = 0;
+ *bio_needs_submit = 1;
+ break;
+ }
if (bio_add_page(*bio, page, PAGE_SIZE, 0) ==
PAGE_SIZE) {
@@ -864,6 +874,7 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
struct bio *bio = *fio->bio;
struct page *page = fio->encrypted_page ?
fio->encrypted_page : fio->page;
+ int bio_needs_submit = 0;
if (!f2fs_is_valid_blkaddr(fio->sbi, fio->new_blkaddr,
__is_meta_io(fio) ? META_GENERIC : DATA_GENERIC))
@@ -872,11 +883,6 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
trace_f2fs_submit_page_bio(page, fio);
f2fs_trace_ios(fio, 0);
- if (bio && (!page_is_mergeable(fio->sbi, bio, *fio->last_block,
- fio->new_blkaddr) ||
- !f2fs_crypt_mergeable_bio(bio, fio->page->mapping->host,
- fio->page->index, fio)))
- f2fs_submit_merged_ipu_write(fio->sbi, &bio, NULL);
alloc_new:
if (!bio) {
bio = __bio_alloc(fio, BIO_MAX_PAGES);
@@ -886,8 +892,12 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
add_bio_entry(fio->sbi, bio, page, fio->temp);
} else {
- if (add_ipu_page(fio->sbi, &bio, page))
+ if (add_ipu_page(fio, &bio, page, &bio_needs_submit))
+ goto alloc_new;
+ if (bio_needs_submit) {
+ f2fs_submit_merged_ipu_write(fio->sbi, &bio, NULL);
goto alloc_new;
+ }
}
if (fio->io_wbc)
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project.
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