scrub_setup_recheck_block() calls btrfs_map_sblock() and then access
bbio without protection of bio_counter.
This can leads to use-after-free if racing with dev replace cancel.
Fix it by increasing bio_counter before calling btrfs_map_sblock() and
decrease the bio_counter when corresponding recover is finished.
Cc: Liu Bo <bo.li....@oracle.com>
Reported-by: Liu Bo <bo.li....@oracle.com>
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
fs/btrfs/scrub.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index b8c49074d1b3..84b077c993c0 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1072,9 +1072,11 @@ static inline void scrub_get_recover(struct
scrub_recover *recover)
atomic_inc(&recover->refs);
}
-static inline void scrub_put_recover(struct scrub_recover *recover)
+static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
+ struct scrub_recover *recover)
{
if (atomic_dec_and_test(&recover->refs)) {
+ btrfs_bio_counter_dec(fs_info);
btrfs_put_bbio(recover->bbio);
kfree(recover);
}
@@ -1464,7 +1466,7 @@ static int scrub_handle_errored_block(struct scrub_block
*sblock_to_check)
sblock->pagev[page_index]->sblock = NULL;
recover = sblock->pagev[page_index]->recover;
if (recover) {
- scrub_put_recover(recover);
+ scrub_put_recover(fs_info, recover);
sblock->pagev[page_index]->recover =
NULL;
}
@@ -1556,16 +1558,19 @@ static int scrub_setup_recheck_block(struct scrub_block
*original_sblock,
* with a length of PAGE_SIZE, each returned stripe
* represents one mirror
*/
+ btrfs_bio_counter_inc_blocked(fs_info);
ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
logical, &mapped_length, &bbio, 0, 1);
if (ret || !bbio || mapped_length < sublen) {
btrfs_put_bbio(bbio);
+ btrfs_bio_counter_dec(fs_info);
return -EIO;
}
recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
if (!recover) {
btrfs_put_bbio(bbio);
+ btrfs_bio_counter_dec(fs_info);
return -ENOMEM;
}
@@ -1591,7 +1596,7 @@ static int scrub_setup_recheck_block(struct scrub_block
*original_sblock,
spin_lock(&sctx->stat_lock);
sctx->stat.malloc_errors++;
spin_unlock(&sctx->stat_lock);
- scrub_put_recover(recover);
+ scrub_put_recover(fs_info, recover);
return -ENOMEM;
}
scrub_page_get(page);
@@ -1633,7 +1638,7 @@ static int scrub_setup_recheck_block(struct scrub_block
*original_sblock,
scrub_get_recover(recover);
page->recover = recover;
}
- scrub_put_recover(recover);
+ scrub_put_recover(fs_info, recover);
length -= sublen;
logical += sublen;
page_index++;
--
2.12.1
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