From 13dce204cf6f3f0f49c9949971052a4c9657c0c0 Mon Sep 17 00:00:00 2001 From: Darren Kenny Date: Tue, 29 Mar 2022 15:52:46 +0000 Subject: [PATCH 4/5] fs/btrfs: Fix more ASAN and SEGV issues found with fuzzing The fuzzer is generating btrfs file systems that have chunks with invalid combinations of stripes and substripes for the given RAID configurations. After examining the Linux kernel fs/btrfs/tree-checker.c code, it appears that sub-stripes should only be applied to RAID10, and in that case there should only ever be 2 of them. Similarly, RAID single should only have 1 stripe, and RAID1/1C3/1C4 should have 2. 3 or 4 stripes respectively, which is what redundancy corresponds. Some of the chunks ended up with a size of 0, which grub_malloc() still returned memory for and in turn generated ASAN errors later when accessed. While it would be possible to specifically limit the number of stripes, a more correct test was on the combination of the chunk item, and the number of stripes by the size of the chunk stripe structure in comparison to the size of the chunk itself. Signed-off-by: Darren Kenny Reviewed-by: Daniel Kiper --- grub-core/fs/btrfs.c | 55 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c index 139c6616d..73b230632 100644 --- a/grub-core/fs/btrfs.c +++ b/grub-core/fs/btrfs.c @@ -912,6 +912,12 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, return grub_error (GRUB_ERR_BAD_FS, "couldn't find the chunk descriptor"); + if (!chsize) + { + grub_dprintf ("btrfs", "zero-size chunk\n"); + return grub_error (GRUB_ERR_BAD_FS, + "got an invalid zero-size chunk"); + } chunk = grub_malloc (chsize); if (!chunk) return grub_errno; @@ -970,6 +976,16 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, stripe_length = grub_divmod64 (grub_le_to_cpu64 (chunk->size), nstripes, NULL); + + /* For single, there should be exactly 1 stripe. */ + if (grub_le_to_cpu16 (chunk->nstripes) != 1) + { + grub_dprintf ("btrfs", "invalid RAID_SINGLE: nstripes != 1 (%u)\n", + grub_le_to_cpu16 (chunk->nstripes)); + return grub_error (GRUB_ERR_BAD_FS, + "invalid RAID_SINGLE: nstripes != 1 (%u)", + grub_le_to_cpu16 (chunk->nstripes)); + } if (stripe_length == 0) stripe_length = 512; stripen = grub_divmod64 (off, stripe_length, &stripe_offset); @@ -989,6 +1005,19 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, stripen = 0; stripe_offset = off; csize = grub_le_to_cpu64 (chunk->size) - off; + + /* + * Redundancy, and substripes only apply to RAID10, and there + * should be exactly 2 sub-stripes. + */ + if (grub_le_to_cpu16 (chunk->nstripes) != redundancy) + { + grub_dprintf ("btrfs", "invalid RAID1: nstripes != %u (%u)\n", + redundancy, grub_le_to_cpu16 (chunk->nstripes)); + return grub_error (GRUB_ERR_BAD_FS, + "invalid RAID1: nstripes != %u (%u)", + redundancy, grub_le_to_cpu16 (chunk->nstripes)); + } break; } case GRUB_BTRFS_CHUNK_TYPE_RAID0: @@ -1025,6 +1054,20 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, stripe_offset = low + chunk_stripe_length * high; csize = chunk_stripe_length - low; + + /* + * Substripes only apply to RAID10, and there + * should be exactly 2 sub-stripes. + */ + if (grub_le_to_cpu16 (chunk->nsubstripes) != 2) + { + grub_dprintf ("btrfs", "invalid RAID10: nsubstripes != 2 (%u)", + grub_le_to_cpu16 (chunk->nsubstripes)); + return grub_error (GRUB_ERR_BAD_FS, + "invalid RAID10: nsubstripes != 2 (%u)", + grub_le_to_cpu16 (chunk->nsubstripes)); + } + break; } case GRUB_BTRFS_CHUNK_TYPE_RAID5: @@ -1124,6 +1167,8 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, for (j = 0; j < 2; j++) { + grub_size_t est_chunk_alloc = 0; + grub_dprintf ("btrfs", "chunk 0x%" PRIxGRUB_UINT64_T "+0x%" PRIxGRUB_UINT64_T " (%d stripes (%d substripes) of %" @@ -1136,6 +1181,16 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr, grub_dprintf ("btrfs", "reading laddr 0x%" PRIxGRUB_UINT64_T "\n", addr); + if (grub_mul (sizeof (struct grub_btrfs_chunk_stripe), + grub_le_to_cpu16 (chunk->nstripes), &est_chunk_alloc) || + grub_add (est_chunk_alloc, + sizeof (struct grub_btrfs_chunk_item), &est_chunk_alloc) || + est_chunk_alloc > chunk->size) + { + err = GRUB_ERR_BAD_FS; + break; + } + if (is_raid56) { err = btrfs_read_from_chunk (data, chunk, stripen, -- 2.33.5