On Tue, 20 Aug 2024 19:34:18 -0400, Kent Overstreet wrote: > > When journal v2 entry nr overflow, it will cause the value of ja->nr to > > be incorrect, this will result in the allocated memory to ja->buckets > > being too small, leading to out of bounds access in bch2_dev_journal_init. > > > > Reported-by: syzbot+47ecc948aadfb2ab3...@syzkaller.appspotmail.com > > Signed-off-by: Lizhi Xu <lizhi...@windriver.com> > > --- > > fs/bcachefs/journal_sb.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/fs/bcachefs/journal_sb.c b/fs/bcachefs/journal_sb.c > > index db80e506e3ab..db2b2100e4e5 100644 > > --- a/fs/bcachefs/journal_sb.c > > +++ b/fs/bcachefs/journal_sb.c > > @@ -119,6 +119,11 @@ static int bch2_sb_journal_v2_validate(struct bch_sb > > *sb, struct bch_sb_field *f > > for (i = 0; i < nr; i++) { > > b[i].start = le64_to_cpu(journal->d[i].start); > > b[i].end = b[i].start + le64_to_cpu(journal->d[i].nr); > > + if (le64_to_cpu(journal->d[i].nr) > UINT_MAX) { > > + prt_printf(err, "journal v2 entry d[%u].nr %llu > > overflow\n", > > + i, le64_to_cpu(journal->d[i].nr)); > > + goto err; > > + } > > no, you need to sum up _all_ the entries and verify the total doesn't > overflow UINT_MAX The overflow value of le64_to_cpu(journal->d[i].nr) is 18446744073709551615(for u64), or in other words, it is -1 for s64.
Therefore, the existing check for single entry is retained, and an overflow check for the total value of all entry is will added. BR, Lizhi