linux-kernel - [PATCH V2] Fix minixfs size check

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Date:	Tue, 15 May 2012 01:38:54 +0200
From:	Vladimir 'φ-coder/phcoder' Serbinenko 
	<phcoder@...il.com>
To:	Jan Kara <jack@...e.cz>
CC:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH V2] Fix minixfs size check


>   Oh, right. Then your patch should be OK, just it's enough to cast one of
> the arguments to u64.

I know. I just consider it clearer and less risk to lose it in the future.
Moreover it avoids thinking of how much is really needed

> And BTW looking at minix, it should also set
> s_maxbytes to s_max_size. Otherwise it will be always limited by
> MAX_NON_LFS which is 2^31-1.


Patch here:

 minixfs file size check is buggy and it doesn't allow
 creating a block which can't be fully filled

Signed-off-by: Vladimir Serbinenko <phcoder@...il.com>
---
 fs/minix/inode.c    |    1 +
 fs/minix/itree_v1.c |    3 ++-
 fs/minix/itree_v2.c |    3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index fcb05d2..133bb02 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -227,6 +227,7 @@ static int minix_fill_super(struct super_block *s, void *data, int silent)
 	} else
 		goto out_no_fs;
 
+	s->s_maxbytes = sbi->s_max_size;
 	/*
 	 * Allocate the buffer map to keep the superblock small.
 	 */
diff --git a/fs/minix/itree_v1.c b/fs/minix/itree_v1.c
index 282e15a..4f8f8b2 100644
--- a/fs/minix/itree_v1.c
+++ b/fs/minix/itree_v1.c
@@ -29,7 +29,8 @@ static int block_to_path(struct inode * inode, long block, int offsets[DEPTH])
 	if (block < 0) {
 		printk("MINIX-fs: block_to_path: block %ld < 0 on dev %s\n",
 			block, bdevname(inode->i_sb->s_bdev, b));
-	} else if (block >= (minix_sb(inode->i_sb)->s_max_size/BLOCK_SIZE)) {
+	} else if ((u64) block * (u64) BLOCK_SIZE
+		   >= minix_sb(inode->i_sb)->s_max_size) {
 		if (printk_ratelimit())
 			printk("MINIX-fs: block_to_path: "
 			       "block %ld too big on dev %s\n",
diff --git a/fs/minix/itree_v2.c b/fs/minix/itree_v2.c
index 13487ad..4a9a19d 100644
--- a/fs/minix/itree_v2.c
+++ b/fs/minix/itree_v2.c
@@ -32,7 +32,8 @@ static int block_to_path(struct inode * inode, long block, int offsets[DEPTH])
 	if (block < 0) {
 		printk("MINIX-fs: block_to_path: block %ld < 0 on dev %s\n",
 			block, bdevname(sb->s_bdev, b));
-	} else if (block >= (minix_sb(inode->i_sb)->s_max_size/sb->s_blocksize)) {
+	} else if ((u64) block * (u64) sb->s_blocksize
+		   >= minix_sb(inode->i_sb)->s_max_size) {
 		if (printk_ratelimit())
 			printk("MINIX-fs: block_to_path: "
 			       "block %ld too big on dev %s\n",


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko


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