FAILED: patch "[PATCH] s390/pkey: Prevent overflow in size calculation for" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] s390/pkey: Prevent overflow in size calculation for" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 7360ee47599af91a1d5f4e74d635d9408a54e489
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025062906-tightwad-overvalue-2006@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7360ee47599af91a1d5f4e74d635d9408a54e489 Mon Sep 17 00:00:00 2001
From: Fedor Pchelkin <pchelkin@ispras.ru>
Date: Wed, 11 Jun 2025 22:20:10 +0300
Subject: [PATCH] s390/pkey: Prevent overflow in size calculation for
 memdup_user()

Number of apqn target list entries contained in 'nr_apqns' variable is
determined by userspace via an ioctl call so the result of the product in
calculation of size passed to memdup_user() may overflow.

In this case the actual size of the allocated area and the value
describing it won't be in sync leading to various types of unpredictable
behaviour later.

Use a proper memdup_array_user() helper which returns an error if an
overflow is detected. Note that it is different from when nr_apqns is
initially zero - that case is considered valid and should be handled in
subsequent pkey_handler implementations.

Found by Linux Verification Center (linuxtesting.org).

Fixes: f2bbc96e7cfa ("s390/pkey: add CCA AES cipher key support")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20250611192011.206057-1-pchelkin@ispras.ru
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index cef60770f68b..b3fcdcae379e 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -86,7 +86,7 @@ static void *_copy_apqns_from_user(void __user *uapqns, size_t nr_apqns)
 	if (!uapqns || nr_apqns == 0)
 		return NULL;
 
-	return memdup_user(uapqns, nr_apqns * sizeof(struct pkey_apqn));
+	return memdup_array_user(uapqns, nr_apqns, sizeof(struct pkey_apqn));
 }
 
 static int pkey_ioctl_genseck(struct pkey_genseck __user *ugs)

Re: FAILED: patch "[PATCH] s390/pkey: Prevent overflow in size calculation for" failed to apply to 5.4-stable tree

[Holger Dengler]

Hi Greg,

On 29/06/2025 14:41, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 5.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
> git checkout FETCH_HEAD
> git cherry-pick -x 7360ee47599af91a1d5f4e74d635d9408a54e489
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025062906-tightwad-overvalue-2006@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
> 
> Possible dependencies:

The main reason for the failure is, that the error-path implementation has changed after 5.4. But even if the patch is adopted accordingly, it will still require memdup_array_user(), which is currently missing in 5.4.y and 5.10.y (see my comment to the patch for 5.10.y). 

-- 
Mit freundlichen Grüßen / Kind regards
Holger Dengler
--
IBM Systems, Linux on IBM Z Development
dengler@linux.ibm.com