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bcachefs: Fix sb-downgrade validation

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BugLink: https://bugs.launchpad.net/bugs/2076435

commit 9242a34b760648b722f4958749ad83ef7d0f7525 upstream.

Superblock downgrade entries are only two byte aligned, but section
sizes are 8 byte aligned, which means we have to be careful about
overrun checks; an entry that crosses the end of the section is allowed
(and ignored) as long as it has zero errors.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Portia Stephens <portia.stephens@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>
This commit is contained in:
Kent Overstreet
2024-05-25 12:38:53 -04:00
committed by Stefan Bader
parent 132904b6bf
commit fe0a145e54
1 changed files with 8 additions and 0 deletions
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fs/bcachefs/sb-downgrade.c
+8
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@@ -137,6 +137,14 @@ static int bch2_sb_downgrade_validate(struct bch_sb *sb, struct bch_sb_field *f,
for (const struct bch_sb_field_downgrade_entry *i = e->entries;
(void *) i < vstruct_end(&e->field);
i = downgrade_entry_next_c(i)) {
/*
* Careful: sb_field_downgrade_entry is only 2 byte aligned, but
* section sizes are 8 byte aligned - an empty entry spanning
* the end of the section is allowed (and ignored):
*/
if ((void *) &i->errors[0] > vstruct_end(&e->field))
break;
if (BCH_VERSION_MAJOR(le16_to_cpu(i->version)) !=
BCH_VERSION_MAJOR(le16_to_cpu(sb->version))) {
prt_printf(err, "downgrade entry with mismatched major version (%u != %u)",