[PATCH] macintosh:fix oob read in do_adb_query function

In do_adb_query function of drivers/macintosh/adb.c, req->data is copy
form userland. the  parameter "req->data[2]" is Missing check, the
array size of adb_handler[] is 16, so "adb_handler[
req->data[2]].original_address" and "adb_handler[
req->data[2]].handler_id" will lead to oob read.

Signed-off-by: Ning Qiang <redacted>
---
 drivers/macintosh/adb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/macintosh/adb.c b/drivers/macintosh/adb.c
index 439fab4eaa85..1bbb9ca08d40 100644
--- a/drivers/macintosh/adb.c
+++ b/drivers/macintosh/adb.c

@@ -647,7 +647,7 @@ do_adb_query(struct adb_request *req)
 
 	switch(req->data[1]) {
 	case ADB_QUERY_GETDEVINFO:
-		if (req->nbytes < 3)
+		if (req->nbytes < 3 || req->data[2] >= 16)
 			break;
 		mutex_lock(&adb_handler_mutex);
 		req->reply[0] = adb_handler[req->data[2]].original_address;

-- 
2.25.1

On Wed, Jul 13, 2022 at 11:37:34PM +0800, Ning Qiang wrote:

In do_adb_query function of drivers/macintosh/adb.c, req->data is copy
form userland. the  parameter "req->data[2]" is Missing check, the
array size of adb_handler[] is 16, so "adb_handler[
req->data[2]].original_address" and "adb_handler[
req->data[2]].handler_id" will lead to oob read.

Signed-off-by: Ning Qiang <redacted>

Cc: stable <stable@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

On Wed, Jul 13, 2022 at 11:37:34PM +0800, Ning Qiang wrote:

In do_adb_query function of drivers/macintosh/adb.c, req->data is copy
form userland. the  parameter "req->data[2]" is Missing check, the
array size of adb_handler[] is 16, so "adb_handler[
req->data[2]].original_address" and "adb_handler[
req->data[2]].handler_id" will lead to oob read.

Signed-off-by: Ning Qiang <redacted>

Thanks for catching this!

Do you have a reproducer for this? I'd expect CONFIG_UBSAN_BOUNDS=y to
notice this at runtime, at least.

I'd prefer this was:

+		if (req->nbytes < 3 || req->data[2] >= ARRAY_SIZE(adb_handler))

so it's tied to the actual variable (if its size ever changes).

With that:

Reviewed-by: Kees Cook <redacted>

-Kees

 			break;
 		mutex_lock(&adb_handler_mutex);
 		req->reply[0] = adb_handler[req->data[2]].original_address;
-- 
2.25.1

-- 
Kees Cook

On Wed, 2022-07-13 at 23:37 +0800, Ning Qiang wrote:

In do_adb_query function of drivers/macintosh/adb.c, req->data is
copy
form userland. the  parameter "req->data[2]" is Missing check, the
array size of adb_handler[] is 16, so "adb_handler[
req->data[2]].original_address" and "adb_handler[
req->data[2]].handler_id" will lead to oob read.

Signed-off-by: Ning Qiang <redacted>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

On Wed, 2022-07-13 at 11:53 -0700, Kees Cook wrote:

On Wed, Jul 13, 2022 at 11:37:34PM +0800, Ning Qiang wrote:

quoted

In do_adb_query function of drivers/macintosh/adb.c, req->data is
copy
form userland. the  parameter "req->data[2]" is Missing check, the
array size of adb_handler[] is 16, so "adb_handler[
req->data[2]].original_address" and "adb_handler[
req->data[2]].handler_id" will lead to oob read.

Signed-off-by: Ning Qiang <redacted>

Thanks for catching this!

Do you have a reproducer for this? I'd expect CONFIG_UBSAN_BOUNDS=y
to notice this at runtime, at least.

For that you would need an ancient Mac with an ADB bus which might be
tricky ... I have some in the basement that could possibly be revived
if you really insist but I'd rather not waste the time...

Cheers,
Ben.

quoted

---
 drivers/macintosh/adb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/macintosh/adb.c b/drivers/macintosh/adb.c
index 439fab4eaa85..1bbb9ca08d40 100644
--- a/drivers/macintosh/adb.c
+++ b/drivers/macintosh/adb.c

@@ -647,7 +647,7 @@ do_adb_query(struct adb_request *req)
 
 	switch(req->data[1]) {
 	case ADB_QUERY_GETDEVINFO:
-		if (req->nbytes < 3)
+		if (req->nbytes < 3 || req->data[2] >= 16)

I'd prefer this was:

+		if (req->nbytes < 3 || req->data[2] >=
ARRAY_SIZE(adb_handler))

so it's tied to the actual variable (if its size ever changes).

With that:

Reviewed-by: Kees Cook <redacted>

-Kees

quoted

 			break;
 		mutex_lock(&adb_handler_mutex);
 		req->reply[0] = adb_handler[req-

quoted

data[2]].original_address;

-- 
2.25.1

On Wed, 13 Jul 2022 23:37:34 +0800, Ning Qiang wrote:

In do_adb_query function of drivers/macintosh/adb.c, req->data is copy
form userland. the  parameter "req->data[2]" is Missing check, the
array size of adb_handler[] is 16, so "adb_handler[
req->data[2]].original_address" and "adb_handler[
req->data[2]].handler_id" will lead to oob read.


[...]

Applied to powerpc/next.

[1/1] macintosh:fix oob read in do_adb_query function
      https://git.kernel.org/powerpc/c/fd97e4ad6d3b0c9fce3bca8ea8e6969d9ce7423b

cheers