[PATCH v2] fs: btrfs: fix out of bounds write

[PATCH v2] fs: btrfs: fix out of bounds write

[Alex Shumsky]

Fix btrfs_read/read_and_truncate_page write out of bounds of destination
buffer. Old behavior break bootstd malloc'd buffers of exact file size.
Previously this OOB write have not been noticed because distroboot usually
read files into huge static memory areas.

Signed-off-by: Alex Shumsky <alexthreed@gmail.com>
Fixes: e342718 ("fs: btrfs: Implement btrfs_file_read()")
---

Changes in v2:
- fix error path handling
- add Fixes tag
- use min3

 fs/btrfs/inode.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4691612eda..3998ffc2c8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -640,7 +640,11 @@ static int read_and_truncate_page(struct btrfs_path *path,
 	extent_type = btrfs_file_extent_type(leaf, fi);
 	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 		ret = btrfs_read_extent_inline(path, fi, buf);
-		memcpy(dest, buf + page_off, min(page_len, ret));
+		if (ret < 0) {
+			free(buf);
+			return ret;
+		}
+		memcpy(dest, buf + page_off, min3(page_len, ret, len));
 		free(buf);
 		return len;
 	}
@@ -652,7 +656,7 @@ static int read_and_truncate_page(struct btrfs_path *path,
 		free(buf);
 		return ret;
 	}
-	memcpy(dest, buf + page_off, page_len);
+	memcpy(dest, buf + page_off, min(page_len, len));
 	free(buf);
 	return len;
 }
-- 
2.34.1

Re: [PATCH v2] fs: btrfs: fix out of bounds write

[Qu Wenruo]

在 2024/6/19 07:11, Alex Shumsky 写道:
> Fix btrfs_read/read_and_truncate_page write out of bounds of destination
> buffer. Old behavior break bootstd malloc'd buffers of exact file size.
> Previously this OOB write have not been noticed because distroboot usually
> read files into huge static memory areas.
>
> Signed-off-by: Alex Shumsky <alexthreed@gmail.com>
> Fixes: e342718 ("fs: btrfs: Implement btrfs_file_read()")

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu
> ---
>
> Changes in v2:
> - fix error path handling
> - add Fixes tag
> - use min3
>
>   fs/btrfs/inode.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 4691612eda..3998ffc2c8 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -640,7 +640,11 @@ static int read_and_truncate_page(struct btrfs_path *path,
>   	extent_type = btrfs_file_extent_type(leaf, fi);
>   	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
>   		ret = btrfs_read_extent_inline(path, fi, buf);
> -		memcpy(dest, buf + page_off, min(page_len, ret));
> +		if (ret < 0) {
> +			free(buf);
> +			return ret;
> +		}
> +		memcpy(dest, buf + page_off, min3(page_len, ret, len));
>   		free(buf);
>   		return len;
>   	}
> @@ -652,7 +656,7 @@ static int read_and_truncate_page(struct btrfs_path *path,
>   		free(buf);
>   		return ret;
>   	}
> -	memcpy(dest, buf + page_off, page_len);
> +	memcpy(dest, buf + page_off, min(page_len, len));
>   	free(buf);
>   	return len;
>   }

Re: [PATCH v2] fs: btrfs: fix out of bounds write

[Tom Rini]

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On Tue, Jun 25, 2024 at 01:22:01AM +0300, Alex ThreeD wrote:

> Hi all,
> 
> Is there something on my side needed to push this forward?

I will pick it up for -next in a while, thanks.

> 
> On Wed, Jun 19, 2024 at 12:41 AM Alex Shumsky <alexthreed@gmail.com> wrote:
> 
> > Fix btrfs_read/read_and_truncate_page write out of bounds of destination
> > buffer. Old behavior break bootstd malloc'd buffers of exact file size.
> > Previously this OOB write have not been noticed because distroboot usually
> > read files into huge static memory areas.
> >
> > Signed-off-by: Alex Shumsky <alexthreed@gmail.com>
> > Fixes: e342718 ("fs: btrfs: Implement btrfs_file_read()")
> > ---
> >
> > Changes in v2:
> > - fix error path handling
> > - add Fixes tag
> > - use min3
> >
> >  fs/btrfs/inode.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> > index 4691612eda..3998ffc2c8 100644
> > --- a/fs/btrfs/inode.c
> > +++ b/fs/btrfs/inode.c
> > @@ -640,7 +640,11 @@ static int read_and_truncate_page(struct btrfs_path
> > *path,
> >         extent_type = btrfs_file_extent_type(leaf, fi);
> >         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
> >                 ret = btrfs_read_extent_inline(path, fi, buf);
> > -               memcpy(dest, buf + page_off, min(page_len, ret));
> > +               if (ret < 0) {
> > +                       free(buf);
> > +                       return ret;
> > +               }
> > +               memcpy(dest, buf + page_off, min3(page_len, ret, len));
> >                 free(buf);
> >                 return len;
> >         }
> > @@ -652,7 +656,7 @@ static int read_and_truncate_page(struct btrfs_path
> > *path,
> >                 free(buf);
> >                 return ret;
> >         }
> > -       memcpy(dest, buf + page_off, page_len);
> > +       memcpy(dest, buf + page_off, min(page_len, len));
> >         free(buf);
> >         return len;
> >  }
> > --
> > 2.34.1
> >
> >

-- 
Tom

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Re: [PATCH v2] fs: btrfs: fix out of bounds write

[Tom Rini]

On Wed, 19 Jun 2024 00:41:38 +0300, Alex Shumsky wrote:

> Fix btrfs_read/read_and_truncate_page write out of bounds of destination
> buffer. Old behavior break bootstd malloc'd buffers of exact file size.
> Previously this OOB write have not been noticed because distroboot usually
> read files into huge static memory areas.
> 
> 

Applied to u-boot/next, thanks!

-- 
Tom