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bcachefs: slab-use-after-free Read in bch2_sb_errors_from_cpu

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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>
This commit is contained in:
Pei Li 2024-06-25 13:04:59 -07:00 committed by Kent Overstreet
parent 89d21b69b4
commit 211c581de2
1 changed files with 10 additions and 4 deletions
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14
fs/bcachefs/sb-errors.c
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@ -110,19 +110,25 @@ out:
void bch2_sb_errors_from_cpu(struct bch_fs *c) void bch2_sb_errors_from_cpu(struct bch_fs *c)
{ {
bch_sb_errors_cpu *src = &c->fsck_error_counts; bch_sb_errors_cpu *src = &c->fsck_error_counts;
struct bch_sb_field_errors *dst = struct bch_sb_field_errors *dst;
bch2_sb_field_resize(&c->disk_sb, errors,
bch2_sb_field_errors_u64s(src->nr));
unsigned i; 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) if (!dst)
return; goto err;
for (i = 0; i < src->nr; i++) { 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_ID(&dst->entries[i], src->data[i].id);
SET_BCH_SB_ERROR_ENTRY_NR(&dst->entries[i], src->data[i].nr); 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); 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) static int bch2_sb_errors_to_cpu(struct bch_fs *c)