The journal revoke block recovery code does not check r_count for sanity, which means that an evil value of r_count could result in the kernel reading off the end of the revoke table and into whatever garbage lies beyond. This could crash the kernel, so fix that. However, in testing this fix, I discovered that the code to write out the revoke tables also was not correctly checking to see if the block was full -- the current offset check is fine so long as the revoke table space size is a multiple of the record size, but this is not true when either journal_csum_v[23] are set.
Unified · Split
| @@ -842,15 +842,23 @@ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh, · 841 unmodified lines | ||
| 842 | 842 | { |
| 843 | 843 | jbd2_journal_revoke_header_t *header; |
| 844 | 844 | int offset, max; |
| 845 | + int csum_size = 0; | |
| 846 | + __u32 rcount; | |
| 845 | 847 | int record_len = 4; |
| 846 | 848 | |
| 847 | 849 | header = (jbd2_journal_revoke_header_t *) bh->b_data; |
| 848 | 850 | offset = sizeof(jbd2_journal_revoke_header_t); |
| 849 | − max = be32_to_cpu(header->r_count); | |
| 851 | + rcount = be32_to_cpu(header->r_count); | |
| 850 | 852 | |
| 851 | 853 | if (!jbd2_revoke_block_csum_verify(journal, header)) |
| 852 | 854 | return -EINVAL; |
| 853 | 855 | |
| 856 | + if (jbd2_journal_has_csum_v2or3(journal)) | |
| 857 | + csum_size = sizeof(struct jbd2_journal_revoke_tail); | |
| 858 | + if (rcount > journal->j_blocksize - csum_size) | |
| 859 | + return -EINVAL; | |
| 860 | + max = rcount; | |
| 861 | + | |
| 854 | 862 | if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) |
| 855 | 863 | record_len = 8; |
| 856 | 864 | |
| @@ -577,7 +577,7 @@ static void write_one_revoke_record(journal_t *journal, · 576 unmodified lines | ||
| 577 | 577 | { |
| 578 | 578 | int csum_size = 0; |
| 579 | 579 | struct buffer_head *descriptor; |
| 580 | − int offset; | |
| 580 | + int sz, offset; | |
| 581 | 581 | journal_header_t *header; |
| 582 | 582 | |
| 583 | 583 | /* If we are already aborting, this all becomes a noop. We |
| @@ -594,9 +594,14 @@ static void write_one_revoke_record(journal_t *journal, · 10 unmodified lines | ||
| 594 | 594 | if (jbd2_journal_has_csum_v2or3(journal)) |
| 595 | 595 | csum_size = sizeof(struct jbd2_journal_revoke_tail); |
| 596 | 596 | |
| 597 | + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) | |
| 598 | + sz = 8; | |
| 599 | + else | |
| 600 | + sz = 4; | |
| 601 | + | |
| 597 | 602 | /* Make sure we have a descriptor with space left for the record */ |
| 598 | 603 | if (descriptor) { |
| 599 | − if (offset >= journal->j_blocksize - csum_size) { | |
| 604 | + if (offset + sz > journal->j_blocksize - csum_size) { | |
| 600 | 605 | flush_descriptor(journal, descriptor, offset, write_op); |
| 601 | 606 | descriptor = NULL; |
| 602 | 607 | } |
| @@ -619,16 +624,13 @@ static void write_one_revoke_record(journal_t *journal, · 16 unmodified lines | ||
| 619 | 624 | *descriptorp = descriptor; |
| 620 | 625 | } |
| 621 | 626 | |
| 622 | − if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) { | |
| 627 | + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) | |
| 623 | 628 | * ((__be64 *)(&descriptor->b_data[offset])) = |
| 624 | 629 | cpu_to_be64(record->blocknr); |
| 625 | − offset += 8; | |
| 626 | − | |
| 627 | − } else { | |
| 630 | + else | |
| 628 | 631 | * ((__be32 *)(&descriptor->b_data[offset])) = |
| 629 | 632 | cpu_to_be32(record->blocknr); |
| 630 | − offset += 4; | |
| 631 | − } | |
| 633 | + offset += sz; | |
| 632 | 634 | |
| 633 | 635 | *offsetp = offset; |
| 634 | 636 | } |