On 6/17/24 11:33, Dan Carpenter wrote:
Use kmemdup_array() because we're allocating an array.
The main difference between kmemdup() and kmemdup_array() is that the
kmemdup_array() function has integer overflow checking built it. The
"args->in_sync.count" variable is a u32 so integer overflows would only
be a concern on 32bit systems. Fortunately, however, the u_memcpya()
function has integer overflow checking which means that it is not an
issue.
Still using kmemdup_array() is more appropriate and makes auditing the
code easier.
Indeed, we shouldn't rely on the previous check here, good catch.
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_sched.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_sched.c b/drivers/gpu/drm/nouveau/nouveau_sched.c
index 32fa2e273965..53d8b0584a56 100644
--- a/drivers/gpu/drm/nouveau/nouveau_sched.c
+++ b/drivers/gpu/drm/nouveau/nouveau_sched.c
@@ -45,10 +45,10 @@ nouveau_job_init(struct nouveau_job *job,
if (job->sync)
return -EINVAL;
- job->in_sync.data = kmemdup(args->in_sync.s,
- sizeof(*args->in_sync.s) *
- args->in_sync.count,
- GFP_KERNEL);
+ job->in_sync.data = kmemdup_array(args->in_sync.s,
+ args->in_sync.count,
+ sizeof(*args->in_sync.s),
+ GFP_KERNEL);
if (!job->in_sync.data)
return -ENOMEM;
Not sure if this is what we want for kmemdup_array(). It just saturates the
size. This doesn't prevent accessing the array out of bounds later on. I mean,
it's rather unlikely to get such a huge amount of physically contiguous memory
anyways, but wouldn't it be cleaner to let kmemdup_array() return
ERR_PTR(-EOVERFLOW) on overflow, just like memdup_array_user()[1]?
AFAICS, there's just two users of kmemdup_array(), hence it should be an easy
change. :-)
[1] https://elixir.bootlin.com/linux/latest/source/include/linux/string.h#L30
}
@@ -60,10 +60,10 @@ nouveau_job_init(struct nouveau_job *job,
goto err_free_in_sync;
}
- job->out_sync.data = kmemdup(args->out_sync.s,
- sizeof(*args->out_sync.s) *
- args->out_sync.count,
- GFP_KERNEL);
+ job->out_sync.data = kmemdup_array(args->out_sync.s,
+ args->out_sync.count,
+ sizeof(*args->out_sync.s),
+ GFP_KERNEL);
if (!job->out_sync.data) {
ret = -ENOMEM;
goto err_free_in_sync;
