Ocfs2 devel - May 2023 - [PATCH] ocfs2: check new file size on fallocate call

When changing a file size with fallocate() the new size isn't being
checked.  In particular, the FSIZE ulimit isn't being checked, which makes
fstest generic/228 fail.  Simply adding a call to inode_newsize_ok() fixes
this issue.

Signed-off-by: Lu?s Henriques <lhenriques at suse.de>
---
 fs/ocfs2/file.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index efb09de4343d..b173c36bcab3 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2100,14 +2100,20 @@ static long ocfs2_fallocate(struct file *file, int mode,
loff_t offset,
 	struct ocfs2_space_resv sr;
 	int change_size = 1;
 	int cmd = OCFS2_IOC_RESVSP64;
+	int ret = 0;
 
 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 		return -EOPNOTSUPP;
 	if (!ocfs2_writes_unwritten_extents(osb))
 		return -EOPNOTSUPP;
 
-	if (mode & FALLOC_FL_KEEP_SIZE)
+	if (mode & FALLOC_FL_KEEP_SIZE) {
 		change_size = 0;
+	} else {
+		ret = inode_newsize_ok(inode, offset + len);
+		if (ret)
+			return ret;
+	}
 
 	if (mode & FALLOC_FL_PUNCH_HOLE)
 		cmd = OCFS2_IOC_UNRESVSP64;

On Mon, May 29, 2023 at 8:26?AM Lu?s Henriques <lhenriques at suse.de>
wrote:
>
> When changing a file size with fallocate() the new size isn't being
> checked.  In particular, the FSIZE ulimit isn't being checked, which
makes
> fstest generic/228 fail.  Simply adding a call to inode_newsize_ok() fixes
> this issue.
>
> Signed-off-by: Lu?s Henriques <lhenriques at suse.de>
Looks good, thanks Luis.

Reviewed-by: Mark Fasheh <mark at fasheh.com>

On 5/29/23 11:26 PM, Lu?s Henriques wrote:
> When changing a file size with fallocate() the new size isn't being
> checked.  In particular, the FSIZE ulimit isn't being checked, which
makes
> fstest generic/228 fail.  Simply adding a call to inode_newsize_ok() fixes
> this issue.
> 
> Signed-off-by: Lu?s Henriques <lhenriques at suse.de>
> ---
>  fs/ocfs2/file.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index efb09de4343d..b173c36bcab3 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2100,14 +2100,20 @@ static long ocfs2_fallocate(struct file *file, int
mode, loff_t offset,
>  	struct ocfs2_space_resv sr;
>  	int change_size = 1;
>  	int cmd = OCFS2_IOC_RESVSP64;
> +	int ret = 0;
>  
>  	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
>  		return -EOPNOTSUPP;
This means we only support keep-size and pouch_hole.
And it seems pouch_hole will also imply keep-size.
>  	if (!ocfs2_writes_unwritten_extents(osb))
>  		return -EOPNOTSUPP;
>  
> -	if (mode & FALLOC_FL_KEEP_SIZE)
> +	if (mode & FALLOC_FL_KEEP_SIZE) {
>  		change_size = 0;
> +	} else {
Seems this will be a dead branch?

Thanks,
Joseph
> +		ret = inode_newsize_ok(inode, offset + len);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	if (mode & FALLOC_FL_PUNCH_HOLE)
>  		cmd = OCFS2_IOC_UNRESVSP64;

On 5/29/23 11:26 PM, Lu?s Henriques wrote:
> When changing a file size with fallocate() the new size isn't being
> checked.  In particular, the FSIZE ulimit isn't being checked, which
makes
> fstest generic/228 fail.  Simply adding a call to inode_newsize_ok() fixes
> this issue.
> 
> Signed-off-by: Lu?s Henriques <lhenriques at suse.de>
Reviewed-by: Joseph Qi <joseph.qi at
linux.alibaba.com>
> ---
>  fs/ocfs2/file.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index efb09de4343d..b173c36bcab3 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2100,14 +2100,20 @@ static long ocfs2_fallocate(struct file *file, int
mode, loff_t offset,
>  	struct ocfs2_space_resv sr;
>  	int change_size = 1;
>  	int cmd = OCFS2_IOC_RESVSP64;
> +	int ret = 0;
>  
>  	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
>  		return -EOPNOTSUPP;
>  	if (!ocfs2_writes_unwritten_extents(osb))
>  		return -EOPNOTSUPP;
>  
> -	if (mode & FALLOC_FL_KEEP_SIZE)
> +	if (mode & FALLOC_FL_KEEP_SIZE) {
>  		change_size = 0;
> +	} else {
> +		ret = inode_newsize_ok(inode, offset + len);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	if (mode & FALLOC_FL_PUNCH_HOLE)
>  		cmd = OCFS2_IOC_UNRESVSP64;

On Mon, 29 May 2023 16:26:45 +0100 Lu?s Henriques via Ocfs2-devel
<ocfs2-devel at oss.oracle.com> wrote:
> When changing a file size with fallocate() the new size isn't being
> checked.  In particular, the FSIZE ulimit isn't being checked, which
makes
> fstest generic/228 fail.  Simply adding a call to inode_newsize_ok() fixes
> this issue.
> 
> ...
>
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2100,14 +2100,20 @@ static long ocfs2_fallocate(struct file *file, int
mode, loff_t offset,
>  	struct ocfs2_space_resv sr;
>  	int change_size = 1;
>  	int cmd = OCFS2_IOC_RESVSP64;
> +	int ret = 0;
>  
>  	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
>  		return -EOPNOTSUPP;
>  	if (!ocfs2_writes_unwritten_extents(osb))
>  		return -EOPNOTSUPP;
>  
> -	if (mode & FALLOC_FL_KEEP_SIZE)
> +	if (mode & FALLOC_FL_KEEP_SIZE) {
>  		change_size = 0;
> +	} else {
> +		ret = inode_newsize_ok(inode, offset + len);
> +		if (ret)
> +			return ret;
> +	}
>  
So userspace can exceed rlimit(RLIMIT_FSIZE).

Do we think this flaw is serious enough to justify backporting the fix
into earlier -stable kernels?