[PATCH] fs/squashfs: Fix Coverity Scan defects

Joao Marcos Costa
2020-09-11T10:21:06Z

Fix control flow issues and null pointer dereferences.

Signed-off-by: Joao Marcos Costa <jmcosta944@gmail.com>
---
fs/squashfs/sqfs.c | 20 +++++++++++++-------
fs/squashfs/sqfs_dir.c | 3 +--
fs/squashfs/sqfs_inode.c | 5 ++++-
3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c
index f67f7c4a40..15208b4dab 100644
--- a/fs/squashfs/sqfs.c
+++ b/fs/squashfs/sqfs.c
@@ -154,7 +154,7 @@ static int sqfs_frag_lookup(u32 inode_fragment_index,
header = get_unaligned_le16(metadata_buffer + table_offset);
metadata = metadata_buffer + table_offset + SQFS_HEADER_SIZE;

- if (!metadata) {
+ if (!metadata || !header) {
ret = -ENOMEM;
goto free_buffer;
}
@@ -434,9 +434,9 @@ static int sqfs_search_dir(struct squashfs_dir_stream *dirs, char **token_list,
{
struct squashfs_super_block *sblk = ctxt.sblk;
char *path, *target, **sym_tokens, *res, *rem;
- struct squashfs_ldir_inode *ldir = NULL;
int j, ret, new_inode_number, offset;
struct squashfs_symlink_inode *sym;
+ struct squashfs_ldir_inode *ldir;
struct squashfs_dir_inode *dir;
struct fs_dir_stream *dirsp;
struct fs_dirent *dent;
@@ -448,8 +448,8 @@ static int sqfs_search_dir(struct squashfs_dir_stream *dirs, char **token_list,
table = sqfs_find_inode(dirs->inode_table, le32_to_cpu(sblk->inodes),
sblk->inodes, sblk->block_size);

- /* root is a regular directory, not an extended one */
dir = (struct squashfs_dir_inode *)table;
+ ldir = (struct squashfs_ldir_inode *)table;

/* get directory offset in directory table */
offset = sqfs_dir_offset(table, m_list, m_count);
@@ -1146,7 +1146,10 @@ static int sqfs_get_regfile_info(struct squashfs_reg_inode *reg,
finfo->start = get_unaligned_le32(&reg->start_block);
finfo->frag = SQFS_IS_FRAGMENTED(get_unaligned_le32(&reg->fragment));

- if (finfo->size < 1 || finfo->offset < 0 || finfo->start < 0)
+ if (finfo->frag && finfo->offset == 0xFFFFFFFF)
+ return -EINVAL;
+
+ if (finfo->size < 1 || finfo->start == 0xFFFFFFFF)
return -EINVAL;

if (finfo->frag) {
@@ -1156,7 +1159,7 @@ static int sqfs_get_regfile_info(struct squashfs_reg_inode *reg,
if (ret < 0)
return -EINVAL;
finfo->comp = true;
- if (fentry->size < 1 || fentry->start < 0)
+ if (fentry->size < 1 || fentry->start == 0x7FFFFFFF)
return -EINVAL;
} else {
datablk_count = DIV_ROUND_UP(finfo->size, le32_to_cpu(blksz));
@@ -1181,7 +1184,10 @@ static int sqfs_get_lregfile_info(struct squashfs_lreg_inode *lreg,
finfo->start = get_unaligned_le64(&lreg->start_block);
finfo->frag = SQFS_IS_FRAGMENTED(get_unaligned_le32(&lreg->fragment));

- if (finfo->size < 1 || finfo->offset < 0 || finfo->start < 0)
+ if (finfo->frag && finfo->offset == 0xFFFFFFFF)
+ return -EINVAL;
+
+ if (finfo->size < 1 || finfo->start == 0x7FFFFFFF)
return -EINVAL;

if (finfo->frag) {
@@ -1191,7 +1197,7 @@ static int sqfs_get_lregfile_info(struct squashfs_lreg_inode *lreg,
if (ret < 0)
return -EINVAL;
finfo->comp = true;
- if (fentry->size < 1 || fentry->start < 0)
+ if (fentry->size < 1 || fentry->start == 0x7FFFFFFF)
return -EINVAL;
} else {
datablk_count = DIV_ROUND_UP(finfo->size, le32_to_cpu(blksz));
diff --git a/fs/squashfs/sqfs_dir.c b/fs/squashfs/sqfs_dir.c
index 00d2891e7d..a265b98fe6 100644
--- a/fs/squashfs/sqfs_dir.c
+++ b/fs/squashfs/sqfs_dir.c
@@ -34,8 +34,7 @@ int sqfs_dir_offset(void *dir_i, u32 *m_list, int m_count)
struct squashfs_ldir_inode *ldir;
struct squashfs_dir_inode *dir;
u32 start_block;
- u16 offset;
- int j;
+ int j, offset;

switch (get_unaligned_le16(&base->inode_type)) {
case SQFS_DIR_TYPE:
diff --git a/fs/squashfs/sqfs_inode.c b/fs/squashfs/sqfs_inode.c
index 1387779a85..1368f3063c 100644
--- a/fs/squashfs/sqfs_inode.c
+++ b/fs/squashfs/sqfs_inode.c
@@ -142,8 +142,11 @@ int sqfs_read_metablock(unsigned char *file_mapping, int offset,
u16 header;

data = file_mapping + offset;
+ if (!data)
+ return -EFAULT;
+
header = get_unaligned((u16 *)data);
- if (!header || !data)
+ if (!header)
return -EINVAL;

*compressed = SQFS_COMPRESSED_METADATA(header);
--
2.17.1