From 211c581de28e7741898720b5f74da4e62f37f972 Mon Sep 17 00:00:00 2001
From: Pei Li <peili.dev@gmail.com>
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 <peili.dev@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
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 bda33e59e2264..c1270d790e43b 100644
--- a/fs/bcachefs/sb-errors.c
+++ b/fs/bcachefs/sb-errors.c
@@ -110,19 +110,25 @@ void bch2_sb_error_count(struct bch_fs *c, enum bch_sb_error_id err)
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)
--
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