Replace one-element array with flexible-array member in struct
user_sgmap and refactor the rest of the code, accordingly.

Issue found with the help of Coccinelle and audited and fixed,
manually.

This results in no differences in binary output.

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/ClangBuiltLinux/linux/issues/1851
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/scsi/aacraid/aacraid.h  | 2 +-
 drivers/scsi/aacraid/commctrl.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/aacraid/aacraid.h b/drivers/scsi/aacraid/aacraid.h
index fb3d93e4a99e..7d3f2f7348ff 100644
--- a/drivers/scsi/aacraid/aacraid.h
+++ b/drivers/scsi/aacraid/aacraid.h
@@ -512,7 +512,7 @@ struct sgmap {
 
 struct user_sgmap {
 	u32		count;
-	struct user_sgentry	sg[1];
+	struct user_sgentry	sg[];
 };
 
 struct sgmap64 {
diff --git a/drivers/scsi/aacraid/commctrl.c b/drivers/scsi/aacraid/commctrl.c
index df811ad4afaa..74eb33eb70d3 100644
--- a/drivers/scsi/aacraid/commctrl.c
+++ b/drivers/scsi/aacraid/commctrl.c
@@ -523,7 +523,7 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
 		goto cleanup;
 	}
 
-	if ((fibsize < (sizeof(struct user_aac_srb) - sizeof(struct user_sgentry))) ||
+	if ((fibsize < sizeof(struct user_aac_srb)) ||
 	    (fibsize > (dev->max_fib_size - sizeof(struct aac_fibhdr)))) {
 		rcode = -EINVAL;
 		goto cleanup;
-- 
2.34.1

On Wed, Jun 28, 2023 at 11:57:48AM -0600, Gustavo A. R. Silva wrote:
> Replace one-element array with flexible-array member in struct
> user_sgmap and refactor the rest of the code, accordingly.
> 
> Issue found with the help of Coccinelle and audited and fixed,
> manually.
> 
> This results in no differences in binary output.

Confirmed.

> 
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/ClangBuiltLinux/linux/issues/1851
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook