From cff07e2739d81cf33eb2a378a6136eced852b8cb Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Mon, 17 Jun 2024 10:06:03 -0400 Subject: bcachefs: Guard against overflowing LRU_TIME_BITS LRUs only have 48 bits for the time field (i.e. LRU order); thus we need overflow checks and guards. Reported-by: syzbot+df3bf3f088dcaa728857@syzkaller.appspotmail.com Signed-off-by: Kent Overstreet --- fs/bcachefs/alloc_background.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'fs/bcachefs/alloc_background.h') diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h index ae31a94be6f9..c3cc3c5ba5b6 100644 --- a/fs/bcachefs/alloc_background.h +++ b/fs/bcachefs/alloc_background.h @@ -141,7 +141,13 @@ static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a, !bch2_bucket_sectors_fragmented(ca, a)) return 0; - u64 d = bch2_bucket_sectors_dirty(a); + /* + * avoid overflowing LRU_TIME_BITS on a corrupted fs, when + * bucket_sectors_dirty is (much) bigger than bucket_size + */ + u64 d = min(bch2_bucket_sectors_dirty(a), + ca->mi.bucket_size); + return div_u64(d * (1ULL << 31), ca->mi.bucket_size); } -- cgit v1.2.3-73-gaa49b