From: Kent Overstreet Date: Mon, 6 May 2024 13:16:33 +0000 (-0400) Subject: bcachefs: Fix sb_field_downgrade validation X-Git-Tag: v6.10-rc1~99^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=692aa7a54b2b28d59f24b3bf8250837805484b99;p=thirdparty%2Fkernel%2Flinux.git bcachefs: Fix sb_field_downgrade validation - 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: 84f1638795da ("bcachefs: bch_sb_field_downgrade") Signed-off-by: Kent Overstreet --- diff --git a/fs/bcachefs/sb-downgrade.c b/fs/bcachefs/sb-downgrade.c index 7d2abadbd6e39..390a1bbd2567a 100644 --- a/fs/bcachefs/sb-downgrade.c +++ b/fs/bcachefs/sb-downgrade.c @@ -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)",