[v1] orangefs: fix out-of-bounds fsid access

[PATCH] [RESEND] orangefs: fix out-of-bounds fsid access

Posted by Arnd Bergmann 1 year, 10 months ago

From: Arnd Bergmann <arnd@arndb.de>

orangefs_statfs() copies two consecutive fields of the superblock into
the statfs structure, which triggers a warning from the string fortification
helpers:

In file included from fs/orangefs/super.c:8:
include/linux/fortify-string.h:592:4: error: call to '__read_overflow2_field' declared with 'warning' attribute: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
                        __read_overflow2_field(q_size_field, size);

Change the memcpy() to an individual assignment of the two fields, which helps
both the compiler and human readers understand better what it does.

Link: https://lore.kernel.org/all/20230622101701.3399585-1-arnd@kernel.org/
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org
Cc: Mike Marshall <hubcap@omnibond.com>
Cc: Martin Brandenburg <martin@omnibond.com>
Cc: devel@lists.orangefs.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Resending to VFS maintainers, I sent this a couple of times to the
orangefs maintainers but never got a reply
---
 fs/orangefs/super.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index fb4d09c2f531..152478295766 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -201,7 +201,10 @@ static int orangefs_statfs(struct dentry *dentry, struct kstatfs *buf)
 		     (long)new_op->downcall.resp.statfs.files_avail);
 
 	buf->f_type = sb->s_magic;
-	memcpy(&buf->f_fsid, &ORANGEFS_SB(sb)->fs_id, sizeof(buf->f_fsid));
+	buf->f_fsid = (__kernel_fsid_t) {{
+		ORANGEFS_SB(sb)->fs_id,
+		ORANGEFS_SB(sb)->id,
+	}};
 	buf->f_bsize = new_op->downcall.resp.statfs.block_size;
 	buf->f_namelen = ORANGEFS_NAME_MAX;
 
-- 
2.39.2

Re: [PATCH] [RESEND] orangefs: fix out-of-bounds fsid access

Posted by Jan Kara 1 year, 10 months ago

On Mon 08-04-24 09:50:43, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> orangefs_statfs() copies two consecutive fields of the superblock into
> the statfs structure, which triggers a warning from the string fortification
> helpers:
> 
> In file included from fs/orangefs/super.c:8:
> include/linux/fortify-string.h:592:4: error: call to '__read_overflow2_field' declared with 'warning' attribute: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
>                         __read_overflow2_field(q_size_field, size);
> 
> Change the memcpy() to an individual assignment of the two fields, which helps
> both the compiler and human readers understand better what it does.
> 
> Link: https://lore.kernel.org/all/20230622101701.3399585-1-arnd@kernel.org/
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: Mike Marshall <hubcap@omnibond.com>
> Cc: Martin Brandenburg <martin@omnibond.com>
> Cc: devel@lists.orangefs.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> Resending to VFS maintainers, I sent this a couple of times to the
> orangefs maintainers but never got a reply
> ---
>  fs/orangefs/super.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
> index fb4d09c2f531..152478295766 100644
> --- a/fs/orangefs/super.c
> +++ b/fs/orangefs/super.c
> @@ -201,7 +201,10 @@ static int orangefs_statfs(struct dentry *dentry, struct kstatfs *buf)
>  		     (long)new_op->downcall.resp.statfs.files_avail);
>  
>  	buf->f_type = sb->s_magic;
> -	memcpy(&buf->f_fsid, &ORANGEFS_SB(sb)->fs_id, sizeof(buf->f_fsid));
> +	buf->f_fsid = (__kernel_fsid_t) {{
> +		ORANGEFS_SB(sb)->fs_id,
> +		ORANGEFS_SB(sb)->id,
> +	}};

Frankly, this initializer is hard to understand for me. Why not simple:

	buf->f_fsid[0] = ORANGEFS_SB(sb)->fs_id;
	buf->f_fsid[1] = ORANGEFS_SB(sb)->id;

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] [RESEND] orangefs: fix out-of-bounds fsid access

Posted by Justin Stitt 1 year, 10 months ago

On Mon, Apr 8, 2024 at 7:36 AM Jan Kara <jack@suse.cz> wrote:
> Frankly, this initializer is hard to understand for me. Why not simple:
>
>         buf->f_fsid[0] = ORANGEFS_SB(sb)->fs_id;
>         buf->f_fsid[1] = ORANGEFS_SB(sb)->id;
>

+1 for this idea, seems easier to read for me.

>                                                                 Honza
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR