diff mbox series

[next] udf: Fix undefined behavior bug in struct udf_fileident_iter

Message ID ZRrsYkKIQe8K6F/t@work
State New
Headers
Series [next] udf: Fix undefined behavior bug in struct udf_fileident_iter |

Commit Message

Gustavo A. R. Silva Oct. 2, 2023, 4:14 p.m. UTC 
  `struct fileIdentDesc` is a flexible structure, which means that it
contains a flexible-array member at the bottom. This could potentially
lead to an overwrite of the objects following `fi` in `struct
udf_fileident_iter` at run-time.

Fix this by placing the declaration of object `fi` at the end of
`struct udf_fileident_iter`.

-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.

Fixes: d16076d9b684 ("udf: New directory iteration code")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 fs/udf/udfdecl.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Kees Cook Oct. 2, 2023, 5:38 p.m. UTC | #1 
On Mon, Oct 02, 2023 at 06:14:26PM +0200, Gustavo A. R. Silva wrote:
> `struct fileIdentDesc` is a flexible structure, which means that it
> contains a flexible-array member at the bottom. This could potentially
> lead to an overwrite of the objects following `fi` in `struct
> udf_fileident_iter` at run-time.
> 
> Fix this by placing the declaration of object `fi` at the end of
> `struct udf_fileident_iter`.
> 
> -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
> ready to enable it globally.
> 
> Fixes: d16076d9b684 ("udf: New directory iteration code")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Looks right.

Reviewed-by: Kees Cook <keescook@chromium.org>
Jan Kara Oct. 3, 2023, 9:26 a.m. UTC | #2 
On Mon 02-10-23 18:14:26, Gustavo A. R. Silva wrote:
> `struct fileIdentDesc` is a flexible structure, which means that it
> contains a flexible-array member at the bottom. This could potentially
> lead to an overwrite of the objects following `fi` in `struct
> udf_fileident_iter` at run-time.
> 
> Fix this by placing the declaration of object `fi` at the end of
> `struct udf_fileident_iter`.
> 
> -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
> ready to enable it globally.
> 
> Fixes: d16076d9b684 ("udf: New directory iteration code")
> Cc: stable@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks for the patch! This is in fact harmless since we never use the
impUse field. But I agree it is confusing so I'll merge attached fix
instead.

								Honza
diff mbox series

Patch

diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index 88692512a466..736f591abc89 100644
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -93,11 +93,11 @@  struct udf_fileident_iter {
 	sector_t loffset;		/* Block offset of 'pos' within above
 					 * extent */
 	struct extent_position epos;	/* Position after the above extent */
-	struct fileIdentDesc fi;	/* Copied directory entry */
 	uint8_t *name;			/* Pointer to entry name */
 	uint8_t *namebuf;		/* Storage for entry name in case
 					 * the name is split between two blocks
 					 */
+	struct fileIdentDesc fi;	/* Copied directory entry */
 };
 
 struct udf_vds_record {