From 211c581de28e7741898720b5f74da4e62f37f972 Mon Sep 17 00:00:00 2001 From: Pei Li Date: Tue, 25 Jun 2024 13:04:59 -0700 Subject: [PATCH] bcachefs: slab-use-after-free Read in bch2_sb_errors_from_cpu Acquire fsck_error_counts_lock before accessing the critical section protected by this lock. syzbot has tested the proposed patch and the reproducer did not trigger any issue. Reported-by: syzbot+a2bc0e838efd7663f4d9@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=a2bc0e838efd7663f4d9 Signed-off-by: Pei Li Signed-off-by: Kent Overstreet --- fs/bcachefs/sb-errors.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/bcachefs/sb-errors.c b/fs/bcachefs/sb-errors.c index bda33e59e226..c1270d790e43 100644 --- a/fs/bcachefs/sb-errors.c +++ b/fs/bcachefs/sb-errors.c @@ -110,19 +110,25 @@ out: void bch2_sb_errors_from_cpu(struct bch_fs *c) { bch_sb_errors_cpu *src = &c->fsck_error_counts; - struct bch_sb_field_errors *dst = - bch2_sb_field_resize(&c->disk_sb, errors, - bch2_sb_field_errors_u64s(src->nr)); + struct bch_sb_field_errors *dst; unsigned i; + mutex_lock(&c->fsck_error_counts_lock); + + dst = bch2_sb_field_resize(&c->disk_sb, errors, + bch2_sb_field_errors_u64s(src->nr)); + if (!dst) - return; + goto err; for (i = 0; i < src->nr; i++) { SET_BCH_SB_ERROR_ENTRY_ID(&dst->entries[i], src->data[i].id); SET_BCH_SB_ERROR_ENTRY_NR(&dst->entries[i], src->data[i].nr); dst->entries[i].last_error_time = cpu_to_le64(src->data[i].last_error_time); } + +err: + mutex_unlock(&c->fsck_error_counts_lock); } static int bch2_sb_errors_to_cpu(struct bch_fs *c)