[PATCH V2] FS/OMFS: block number sanity check during fill_super operation

From: Fabian Frederick
Date: Thu Jun 26 2014 - 15:06:15 EST


This patch defines maximum block number to 2^31.
It also converts bitmap_size and array_size to
unsigned int in omfs_get_imap.

Suggested-By: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Suggested-By: Bob Copeland <me@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Bob Copeland <me@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>
---

This is untested.

V2:
use 1ul<<31 instead of 1<<31 to avoid comparing to negative value
(suggested by Linus Torvalds).

fs/omfs/inode.c | 10 +++++++---
fs/omfs/omfs_fs.h | 1 +
2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/omfs/inode.c b/fs/omfs/inode.c
index ec58c76..70d1d93 100644
--- a/fs/omfs/inode.c
+++ b/fs/omfs/inode.c
@@ -306,9 +306,7 @@ static const struct super_operations omfs_sops = {
*/
static int omfs_get_imap(struct super_block *sb)
{
- int bitmap_size;
- int array_size;
- int count;
+ unsigned int bitmap_size, count, array_size;
struct omfs_sb_info *sbi = OMFS_SB(sb);
struct buffer_head *bh;
unsigned long **ptr;
@@ -473,6 +471,12 @@ static int omfs_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_sys_blocksize = be32_to_cpu(omfs_sb->s_sys_blocksize);
mutex_init(&sbi->s_bitmap_lock);

+ if (sbi->s_num_blocks > OMFS_MAX_BLOCKS) {
+ printk(KERN_ERR "omfs: sysblock number (%llx) is out of range\n",
+ (unsigned long long)sbi->s_num_blocks);
+ goto out_brelse_bh;
+ }
+
if (sbi->s_sys_blocksize > PAGE_SIZE) {
printk(KERN_ERR "omfs: sysblock size (%d) is out of range\n",
sbi->s_sys_blocksize);
diff --git a/fs/omfs/omfs_fs.h b/fs/omfs/omfs_fs.h
index ee5e432..83a9833 100644
--- a/fs/omfs/omfs_fs.h
+++ b/fs/omfs/omfs_fs.h
@@ -18,6 +18,7 @@
#define OMFS_XOR_COUNT 19
#define OMFS_MAX_BLOCK_SIZE 8192
#define OMFS_MAX_CLUSTER_SIZE 8
+#define OMFS_MAX_BLOCKS (1ul << 31)

struct omfs_super_block {
char s_fill1[256];
--
1.8.4.5

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