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bcachefs: Fix sb_field_downgrade validation

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- bch2_sb_downgrade_validate() wasn't checking for a downgrade entry
  extending past the end of the superblock section

- for_each_downgrade_entry() is used in to_text() and needs to work on
  malformed input; it also was missing a check for a field extending
  past the end of the section

Reported-by: syzbot+e49ccab73449180bc9be@syzkaller.appspotmail.com
Fixes: 84f1638795 ("bcachefs: bch_sb_field_downgrade")
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-05-06 09:16:33 -04:00
parent a5c3e265d3
commit 692aa7a54b
1 changed files with 12 additions and 2 deletions
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14
fs/bcachefs/sb-downgrade.c
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@ -134,7 +134,8 @@ downgrade_entry_next_c(const struct bch_sb_field_downgrade_entry *e)
#define for_each_downgrade_entry(_d, _i) \
for (const struct bch_sb_field_downgrade_entry *_i = (_d)->entries; \
(void *) _i < vstruct_end(&(_d)->field) && \
(void *) &_i->errors[0] < vstruct_end(&(_d)->field); \
(void *) &_i->errors[0] <= vstruct_end(&(_d)->field) && \
(void *) downgrade_entry_next_c(_i) <= vstruct_end(&(_d)->field); \
_i = downgrade_entry_next_c(_i))
static int bch2_sb_downgrade_validate(struct bch_sb *sb, struct bch_sb_field *f,
@ -142,7 +143,16 @@ static int bch2_sb_downgrade_validate(struct bch_sb *sb, struct bch_sb_field *f,
{
struct bch_sb_field_downgrade *e = field_to_type(f, downgrade);
for_each_downgrade_entry(e, i) {
for (const struct bch_sb_field_downgrade_entry *i = e->entries;
(void *) i < vstruct_end(&e->field);
i = downgrade_entry_next_c(i)) {
if (flags & BCH_VALIDATE_write &&
((void *) &i->errors[0] > vstruct_end(&e->field) ||
(void *) downgrade_entry_next_c(i) > vstruct_end(&e->field))) {
prt_printf(err, "downgrade entry overruns end of superblock section)");
return -BCH_ERR_invalid_sb_downgrade;
}
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)",