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From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: "Gerd Hoffmann" <kraxel@redhat.com>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>
Cc: linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org,
	linaro-mm-sig@lists.linaro.org
Subject: [PATCH] udmabuf: Fix a potential (and unlikely) access to unallocated memory
Date: Mon, 18 Sep 2023 20:46:35 +0200	[thread overview]
Message-ID: <3e37f05c7593f1016f0a46de188b3357cbbd0c0b.1695060389.git.christophe.jaillet@wanadoo.fr> (raw)

If 'list_limit' is set to a very high value, 'lsize' computation could
overflow if 'head.count' is big enough.

In such a case, udmabuf_create() will access to memory beyond 'list'.

Use size_mul() to saturate the value, and have memdup_user() fail.

Fixes: fbb0de795078 ("Add udmabuf misc device")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/dma-buf/udmabuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index c40645999648..fb4c4b5b3332 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -314,13 +314,13 @@ static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg)
 	struct udmabuf_create_list head;
 	struct udmabuf_create_item *list;
 	int ret = -EINVAL;
-	u32 lsize;
+	size_t lsize;
 
 	if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
 		return -EFAULT;
 	if (head.count > list_limit)
 		return -EINVAL;
-	lsize = sizeof(struct udmabuf_create_item) * head.count;
+	lsize = size_mul(sizeof(struct udmabuf_create_item), head.count);
 	list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
 	if (IS_ERR(list))
 		return PTR_ERR(list);
-- 
2.34.1


WARNING: multiple messages have this Message-ID (diff)
From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: "Gerd Hoffmann" <kraxel@redhat.com>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	linux-hardening@vger.kernel.org, linux-media@vger.kernel.org
Subject: [PATCH] udmabuf: Fix a potential (and unlikely) access to unallocated memory
Date: Mon, 18 Sep 2023 20:46:35 +0200	[thread overview]
Message-ID: <3e37f05c7593f1016f0a46de188b3357cbbd0c0b.1695060389.git.christophe.jaillet@wanadoo.fr> (raw)

If 'list_limit' is set to a very high value, 'lsize' computation could
overflow if 'head.count' is big enough.

In such a case, udmabuf_create() will access to memory beyond 'list'.

Use size_mul() to saturate the value, and have memdup_user() fail.

Fixes: fbb0de795078 ("Add udmabuf misc device")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/dma-buf/udmabuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index c40645999648..fb4c4b5b3332 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -314,13 +314,13 @@ static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg)
 	struct udmabuf_create_list head;
 	struct udmabuf_create_item *list;
 	int ret = -EINVAL;
-	u32 lsize;
+	size_t lsize;
 
 	if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
 		return -EFAULT;
 	if (head.count > list_limit)
 		return -EINVAL;
-	lsize = sizeof(struct udmabuf_create_item) * head.count;
+	lsize = size_mul(sizeof(struct udmabuf_create_item), head.count);
 	list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
 	if (IS_ERR(list))
 		return PTR_ERR(list);
-- 
2.34.1


             reply	other threads:[~2023-09-18 18:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-18 18:46 Christophe JAILLET [this message]
2023-09-18 18:46 ` [PATCH] udmabuf: Fix a potential (and unlikely) access to unallocated memory Christophe JAILLET
2023-09-18  3:10 ` Gustavo A. R. Silva
2023-09-18  3:10   ` Gustavo A. R. Silva
2023-09-18 19:22   ` Christophe JAILLET
2023-09-18 19:22     ` Christophe JAILLET
2023-09-24  2:57     ` Kees Cook
2023-09-24  2:57       ` Kees Cook

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