* [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems
@ 2025-01-13 6:17 Dan Carpenter
2025-01-14 7:53 ` Namjae Jeon
0 siblings, 1 reply; 5+ messages in thread
From: Dan Carpenter @ 2025-01-13 6:17 UTC (permalink / raw)
To: Namjae Jeon
Cc: Steve French, Sergey Senozhatsky, Tom Talpey, linux-cifs,
linux-kernel, kernel-janitors
On 32bit systems the addition operations in ipc_msg_alloc() can
potentially overflow leading to memory corruption. Fix this using
size_add() which will ensure that the invalid allocations do not succeed.
In the callers, move the two constant values
"sizeof(struct ksmbd_rpc_command) + 1" onto the same side and use
size_add() for the user controlled values.
Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
I sent this patch in Oct 2023 but it wasn't applied.
https://lore.kernel.org/all/205c4ec1-7c41-4f5d-8058-501fc1b5163c@moroto.mountain/
I reviewed this code again today and it is still an issue.
fs/smb/server/transport_ipc.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
index befaf42b84cc..ec72c97b2f0b 100644
--- a/fs/smb/server/transport_ipc.c
+++ b/fs/smb/server/transport_ipc.c
@@ -242,7 +242,7 @@ static void ipc_update_last_active(void)
static struct ksmbd_ipc_msg *ipc_msg_alloc(size_t sz)
{
struct ksmbd_ipc_msg *msg;
- size_t msg_sz = sz + sizeof(struct ksmbd_ipc_msg);
+ size_t msg_sz = size_add(sz, sizeof(struct ksmbd_ipc_msg));
msg = kvzalloc(msg_sz, KSMBD_DEFAULT_GFP);
if (msg)
@@ -626,8 +626,8 @@ ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len)
struct ksmbd_spnego_authen_request *req;
struct ksmbd_spnego_authen_response *resp;
- msg = ipc_msg_alloc(sizeof(struct ksmbd_spnego_authen_request) +
- blob_len + 1);
+ msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_spnego_authen_request) + 1,
+ blob_len));
if (!msg)
return NULL;
@@ -805,7 +805,8 @@ struct ksmbd_rpc_command *ksmbd_rpc_write(struct ksmbd_session *sess, int handle
struct ksmbd_rpc_command *req;
struct ksmbd_rpc_command *resp;
- msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
+ msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_rpc_command) + 1,
+ payload_sz));
if (!msg)
return NULL;
@@ -853,7 +854,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioctl(struct ksmbd_session *sess, int handle
struct ksmbd_rpc_command *req;
struct ksmbd_rpc_command *resp;
- msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
+ msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_rpc_command) + 1, payload_sz));
if (!msg)
return NULL;
@@ -878,7 +879,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_rap(struct ksmbd_session *sess, void *payloa
struct ksmbd_rpc_command *req;
struct ksmbd_rpc_command *resp;
- msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
+ msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_rpc_command) + 1, payload_sz));
if (!msg)
return NULL;
--
2.45.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems
2025-01-13 6:17 [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems Dan Carpenter
@ 2025-01-14 7:53 ` Namjae Jeon
2025-01-14 10:18 ` Dan Carpenter
0 siblings, 1 reply; 5+ messages in thread
From: Namjae Jeon @ 2025-01-14 7:53 UTC (permalink / raw)
To: Dan Carpenter
Cc: Steve French, Sergey Senozhatsky, Tom Talpey, linux-cifs,
linux-kernel, kernel-janitors
On Mon, Jan 13, 2025 at 3:17 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> On 32bit systems the addition operations in ipc_msg_alloc() can
> potentially overflow leading to memory corruption. Fix this using
> size_add() which will ensure that the invalid allocations do not succeed.
You previously said that memcpy overrun does not occur due to memory
allocation failure with SIZE_MAX.
Would it be better to handle integer overflows as an error before
memory allocation?
And static checkers don't detect memcpy overrun by considering memory
allocation failure?
Thanks.
> In the callers, move the two constant values
> "sizeof(struct ksmbd_rpc_command) + 1" onto the same side and use
> size_add() for the user controlled values.
>
> Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers")
> Cc: stable@vger.kernel.org
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
> I sent this patch in Oct 2023 but it wasn't applied.
> https://lore.kernel.org/all/205c4ec1-7c41-4f5d-8058-501fc1b5163c@moroto.mountain/
> I reviewed this code again today and it is still an issue.
>
> fs/smb/server/transport_ipc.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
> index befaf42b84cc..ec72c97b2f0b 100644
> --- a/fs/smb/server/transport_ipc.c
> +++ b/fs/smb/server/transport_ipc.c
> @@ -242,7 +242,7 @@ static void ipc_update_last_active(void)
> static struct ksmbd_ipc_msg *ipc_msg_alloc(size_t sz)
> {
> struct ksmbd_ipc_msg *msg;
> - size_t msg_sz = sz + sizeof(struct ksmbd_ipc_msg);
> + size_t msg_sz = size_add(sz, sizeof(struct ksmbd_ipc_msg));
>
> msg = kvzalloc(msg_sz, KSMBD_DEFAULT_GFP);
> if (msg)
> @@ -626,8 +626,8 @@ ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len)
> struct ksmbd_spnego_authen_request *req;
> struct ksmbd_spnego_authen_response *resp;
>
> - msg = ipc_msg_alloc(sizeof(struct ksmbd_spnego_authen_request) +
> - blob_len + 1);
> + msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_spnego_authen_request) + 1,
> + blob_len));
> if (!msg)
> return NULL;
>
> @@ -805,7 +805,8 @@ struct ksmbd_rpc_command *ksmbd_rpc_write(struct ksmbd_session *sess, int handle
> struct ksmbd_rpc_command *req;
> struct ksmbd_rpc_command *resp;
>
> - msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
> + msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_rpc_command) + 1,
> + payload_sz));
> if (!msg)
> return NULL;
>
> @@ -853,7 +854,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioctl(struct ksmbd_session *sess, int handle
> struct ksmbd_rpc_command *req;
> struct ksmbd_rpc_command *resp;
>
> - msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
> + msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_rpc_command) + 1, payload_sz));
> if (!msg)
> return NULL;
>
> @@ -878,7 +879,7 @@ struct ksmbd_rpc_command *ksmbd_rpc_rap(struct ksmbd_session *sess, void *payloa
> struct ksmbd_rpc_command *req;
> struct ksmbd_rpc_command *resp;
>
> - msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
> + msg = ipc_msg_alloc(size_add(sizeof(struct ksmbd_rpc_command) + 1, payload_sz));
> if (!msg)
> return NULL;
>
> --
> 2.45.2
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems
2025-01-14 7:53 ` Namjae Jeon
@ 2025-01-14 10:18 ` Dan Carpenter
2025-01-15 0:20 ` Namjae Jeon
0 siblings, 1 reply; 5+ messages in thread
From: Dan Carpenter @ 2025-01-14 10:18 UTC (permalink / raw)
To: Namjae Jeon
Cc: Steve French, Sergey Senozhatsky, Tom Talpey, linux-cifs,
linux-kernel, kernel-janitors
On Tue, Jan 14, 2025 at 04:53:18PM +0900, Namjae Jeon wrote:
> On Mon, Jan 13, 2025 at 3:17 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:
> >
> > On 32bit systems the addition operations in ipc_msg_alloc() can
> > potentially overflow leading to memory corruption. Fix this using
> > size_add() which will ensure that the invalid allocations do not succeed.
> You previously said that memcpy overrun does not occur due to memory
> allocation failure with SIZE_MAX.
>
> Would it be better to handle integer overflows as an error before
> memory allocation?
I mean we could do something like the below patch but I'd prefer to fix
it this way.
> And static checkers don't detect memcpy overrun by considering memory
> allocation failure?
How the struct_size()/array_size() kernel hardenning works is that if
you pass in a too large value instead of wrapping to a small value, the
math results in SIZE_MAX so the allocation will fail. We already handle
allocation failures correctly so it's fine.
The problem in this code is that on 32 bit systems if you chose a "sz"
value which is (unsigned int)-4 then the kvzalloc() allocation will
succeed but the buffer will be 4 bytes smaller than intended and the
"msg->sz = sz;" assignment will corrupt memory.
Anyway, here is how the patch could look like with bounds checking instead
of size_add(). We could fancy it up a bit, but I don't like fancy math.
regards,
dan carpenter
diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
index befaf42b84cc..e1e3bfff163c 100644
--- a/fs/smb/server/transport_ipc.c
+++ b/fs/smb/server/transport_ipc.c
@@ -626,6 +626,9 @@ ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len)
struct ksmbd_spnego_authen_request *req;
struct ksmbd_spnego_authen_response *resp;
+ if (blob_len > INT_MAX)
+ return NULL;
+
msg = ipc_msg_alloc(sizeof(struct ksmbd_spnego_authen_request) +
blob_len + 1);
if (!msg)
@@ -805,6 +808,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_write(struct ksmbd_session *sess, int handle
struct ksmbd_rpc_command *req;
struct ksmbd_rpc_command *resp;
+ if (payload_sz > INT_MAX)
+ return NULL;
+
msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
if (!msg)
return NULL;
@@ -853,6 +859,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioctl(struct ksmbd_session *sess, int handle
struct ksmbd_rpc_command *req;
struct ksmbd_rpc_command *resp;
+ if (payload_sz > INT_MAX)
+ return NULL;
+
msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
if (!msg)
return NULL;
@@ -878,6 +887,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_rap(struct ksmbd_session *sess, void *payloa
struct ksmbd_rpc_command *req;
struct ksmbd_rpc_command *resp;
+ if (payload_sz > INT_MAX)
+ return NULL;
+
msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
if (!msg)
return NULL;
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems
2025-01-14 10:18 ` Dan Carpenter
@ 2025-01-15 0:20 ` Namjae Jeon
2025-01-15 5:26 ` Dan Carpenter
0 siblings, 1 reply; 5+ messages in thread
From: Namjae Jeon @ 2025-01-15 0:20 UTC (permalink / raw)
To: Dan Carpenter
Cc: Steve French, Sergey Senozhatsky, Tom Talpey, linux-cifs,
linux-kernel, kernel-janitors
On Tue, Jan 14, 2025 at 7:18 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> On Tue, Jan 14, 2025 at 04:53:18PM +0900, Namjae Jeon wrote:
> > On Mon, Jan 13, 2025 at 3:17 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:
> > >
> > > On 32bit systems the addition operations in ipc_msg_alloc() can
> > > potentially overflow leading to memory corruption. Fix this using
> > > size_add() which will ensure that the invalid allocations do not succeed.
> > You previously said that memcpy overrun does not occur due to memory
> > allocation failure with SIZE_MAX.
> >
> > Would it be better to handle integer overflows as an error before
> > memory allocation?
>
> I mean we could do something like the below patch but I'd prefer to fix
> it this way.
>
> > And static checkers don't detect memcpy overrun by considering memory
> > allocation failure?
>
> How the struct_size()/array_size() kernel hardenning works is that if
> you pass in a too large value instead of wrapping to a small value, the
> math results in SIZE_MAX so the allocation will fail. We already handle
> allocation failures correctly so it's fine.
>
> The problem in this code is that on 32 bit systems if you chose a "sz"
> value which is (unsigned int)-4 then the kvzalloc() allocation will
> succeed but the buffer will be 4 bytes smaller than intended and the
> "msg->sz = sz;" assignment will corrupt memory.
>
> Anyway, here is how the patch could look like with bounds checking instead
> of size_add(). We could fancy it up a bit, but I don't like fancy math.
Okay, There was a macro for max ipc payload size, So I have changed
INT_MAX to KSMBD_IPC_MAX_PAYLOAD.
I will apply it to #ksmbd-for-next-next.
Thanks!
>
> regards,
> dan carpenter
>
> diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
> index befaf42b84cc..e1e3bfff163c 100644
> --- a/fs/smb/server/transport_ipc.c
> +++ b/fs/smb/server/transport_ipc.c
> @@ -626,6 +626,9 @@ ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len)
> struct ksmbd_spnego_authen_request *req;
> struct ksmbd_spnego_authen_response *resp;
>
> + if (blob_len > INT_MAX)
> + return NULL;
> +
> msg = ipc_msg_alloc(sizeof(struct ksmbd_spnego_authen_request) +
> blob_len + 1);
> if (!msg)
> @@ -805,6 +808,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_write(struct ksmbd_session *sess, int handle
> struct ksmbd_rpc_command *req;
> struct ksmbd_rpc_command *resp;
>
> + if (payload_sz > INT_MAX)
> + return NULL;
> +
> msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
> if (!msg)
> return NULL;
> @@ -853,6 +859,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_ioctl(struct ksmbd_session *sess, int handle
> struct ksmbd_rpc_command *req;
> struct ksmbd_rpc_command *resp;
>
> + if (payload_sz > INT_MAX)
> + return NULL;
> +
> msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
> if (!msg)
> return NULL;
> @@ -878,6 +887,9 @@ struct ksmbd_rpc_command *ksmbd_rpc_rap(struct ksmbd_session *sess, void *payloa
> struct ksmbd_rpc_command *req;
> struct ksmbd_rpc_command *resp;
>
> + if (payload_sz > INT_MAX)
> + return NULL;
> +
> msg = ipc_msg_alloc(sizeof(struct ksmbd_rpc_command) + payload_sz + 1);
> if (!msg)
> return NULL;
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems
2025-01-15 0:20 ` Namjae Jeon
@ 2025-01-15 5:26 ` Dan Carpenter
0 siblings, 0 replies; 5+ messages in thread
From: Dan Carpenter @ 2025-01-15 5:26 UTC (permalink / raw)
To: Namjae Jeon
Cc: Steve French, Sergey Senozhatsky, Tom Talpey, linux-cifs,
linux-kernel, kernel-janitors
On Wed, Jan 15, 2025 at 09:20:54AM +0900, Namjae Jeon wrote:
> On Tue, Jan 14, 2025 at 7:18 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:
> >
> > On Tue, Jan 14, 2025 at 04:53:18PM +0900, Namjae Jeon wrote:
> > > On Mon, Jan 13, 2025 at 3:17 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:
> > > >
> > > > On 32bit systems the addition operations in ipc_msg_alloc() can
> > > > potentially overflow leading to memory corruption. Fix this using
> > > > size_add() which will ensure that the invalid allocations do not succeed.
> > > You previously said that memcpy overrun does not occur due to memory
> > > allocation failure with SIZE_MAX.
> > >
> > > Would it be better to handle integer overflows as an error before
> > > memory allocation?
> >
> > I mean we could do something like the below patch but I'd prefer to fix
> > it this way.
> >
> > > And static checkers don't detect memcpy overrun by considering memory
> > > allocation failure?
> >
> > How the struct_size()/array_size() kernel hardenning works is that if
> > you pass in a too large value instead of wrapping to a small value, the
> > math results in SIZE_MAX so the allocation will fail. We already handle
> > allocation failures correctly so it's fine.
> >
> > The problem in this code is that on 32 bit systems if you chose a "sz"
> > value which is (unsigned int)-4 then the kvzalloc() allocation will
> > succeed but the buffer will be 4 bytes smaller than intended and the
> > "msg->sz = sz;" assignment will corrupt memory.
> >
> > Anyway, here is how the patch could look like with bounds checking instead
> > of size_add(). We could fancy it up a bit, but I don't like fancy math.
> Okay, There was a macro for max ipc payload size, So I have changed
> INT_MAX to KSMBD_IPC_MAX_PAYLOAD.
Nice. I didn't know. Thanks!
regards,
dan carpenter
^ permalink raw reply [flat|nested] 5+ messages in thread
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2025-01-13 6:17 [PATCH RESEND] ksmbd: fix integer overflows on 32 bit systems Dan Carpenter
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