* [PATCH][next] udf: Fix undefined behavior bug in struct udf_fileident_iter
@ 2023-10-02 16:14 Gustavo A. R. Silva
2023-10-02 17:38 ` Kees Cook
2023-10-03 9:26 ` Jan Kara
0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2023-10-02 16:14 UTC (permalink / raw
To: Jan Kara; +Cc: linux-kernel, Gustavo A. R. Silva, linux-hardening
`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(-)
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 {
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH][next] udf: Fix undefined behavior bug in struct udf_fileident_iter
2023-10-02 16:14 [PATCH][next] udf: Fix undefined behavior bug in struct udf_fileident_iter Gustavo A. R. Silva
@ 2023-10-02 17:38 ` Kees Cook
2023-10-03 9:26 ` Jan Kara
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2023-10-02 17:38 UTC (permalink / raw
To: Gustavo A. R. Silva; +Cc: Jan Kara, linux-kernel, linux-hardening
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>
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH][next] udf: Fix undefined behavior bug in struct udf_fileident_iter
2023-10-02 16:14 [PATCH][next] udf: Fix undefined behavior bug in struct udf_fileident_iter Gustavo A. R. Silva
2023-10-02 17:38 ` Kees Cook
@ 2023-10-03 9:26 ` Jan Kara
1 sibling, 0 replies; 3+ messages in thread
From: Jan Kara @ 2023-10-03 9:26 UTC (permalink / raw
To: Gustavo A. R. Silva; +Cc: Jan Kara, linux-kernel, linux-hardening
[-- Attachment #1: Type: text/plain, Size: 863 bytes --]
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
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
[-- Attachment #2: 0001-udf-Avoid-unneeded-variable-length-array-in-struct-f.patch --]
[-- Type: text/x-patch, Size: 1000 bytes --]
From 7b530e7ad261dc6111874f2225c2f38f63d12ebf Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 3 Oct 2023 11:19:02 +0200
Subject: [PATCH] udf: Avoid unneeded variable length array in struct
fileIdentDesc
impUse variable length array in struct fileIdentDesc is never used.
It serves only for documentation purposes of the on-disk format. Remove
it from the struct so that it doesn't confuse the compiler and
reviewers.
Reported-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/udf/ecma_167.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/udf/ecma_167.h b/fs/udf/ecma_167.h
index de17a97e8667..415b050b977d 100644
--- a/fs/udf/ecma_167.h
+++ b/fs/udf/ecma_167.h
@@ -471,7 +471,7 @@ struct fileIdentDesc {
uint8_t lengthFileIdent;
struct long_ad icb;
__le16 lengthOfImpUse;
- uint8_t impUse[];
+ /* uint8_t impUse[]; */
/* uint8_t fileIdent[]; */
/* uint8_t padding[]; */
} __packed;
--
2.35.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
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