squashfs: more metadata hardening
The squashfs fragment reading code doesn't actually verify that the fragment is inside the fragment table. The end result _is_ verified to be inside the image when actually reading the fragment data, but before that is done, we may end up taking a page fault because the fragment table itself might not even exist. Another report from Anatoly and his endless squashfs image fuzzing. Reported-by: Анатолий Тросиненко <anatoly.trosinenko@gmail.com> Acked-by:: Phillip Lougher <phillip.lougher@gmail.com>, Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>hifive-unleashed-5.1
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6b47037682
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71755ee535
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@ -49,11 +49,16 @@ int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment,
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u64 *fragment_block)
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u64 *fragment_block)
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{
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{
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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struct squashfs_sb_info *msblk = sb->s_fs_info;
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int block = SQUASHFS_FRAGMENT_INDEX(fragment);
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int block, offset, size;
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int offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment);
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u64 start_block = le64_to_cpu(msblk->fragment_index[block]);
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struct squashfs_fragment_entry fragment_entry;
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struct squashfs_fragment_entry fragment_entry;
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int size;
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u64 start_block;
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if (fragment >= msblk->fragments)
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return -EIO;
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block = SQUASHFS_FRAGMENT_INDEX(fragment);
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offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment);
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start_block = le64_to_cpu(msblk->fragment_index[block]);
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size = squashfs_read_metadata(sb, &fragment_entry, &start_block,
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size = squashfs_read_metadata(sb, &fragment_entry, &start_block,
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&offset, sizeof(fragment_entry));
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&offset, sizeof(fragment_entry));
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@ -75,6 +75,7 @@ struct squashfs_sb_info {
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unsigned short block_log;
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unsigned short block_log;
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long long bytes_used;
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long long bytes_used;
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unsigned int inodes;
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unsigned int inodes;
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unsigned int fragments;
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int xattr_ids;
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int xattr_ids;
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};
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};
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#endif
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#endif
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@ -175,6 +175,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
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msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
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msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
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msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
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msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
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msblk->inodes = le32_to_cpu(sblk->inodes);
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msblk->inodes = le32_to_cpu(sblk->inodes);
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msblk->fragments = le32_to_cpu(sblk->fragments);
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flags = le16_to_cpu(sblk->flags);
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flags = le16_to_cpu(sblk->flags);
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TRACE("Found valid superblock on %pg\n", sb->s_bdev);
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TRACE("Found valid superblock on %pg\n", sb->s_bdev);
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@ -185,7 +186,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
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TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
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TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
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TRACE("Block size %d\n", msblk->block_size);
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TRACE("Block size %d\n", msblk->block_size);
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TRACE("Number of inodes %d\n", msblk->inodes);
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TRACE("Number of inodes %d\n", msblk->inodes);
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TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
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TRACE("Number of fragments %d\n", msblk->fragments);
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TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
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TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
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TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
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TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
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TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
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TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
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@ -272,7 +273,7 @@ allocate_id_index_table:
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sb->s_export_op = &squashfs_export_ops;
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sb->s_export_op = &squashfs_export_ops;
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handle_fragments:
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handle_fragments:
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fragments = le32_to_cpu(sblk->fragments);
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fragments = msblk->fragments;
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if (fragments == 0)
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if (fragments == 0)
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goto check_directory_table;
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goto check_directory_table;
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