Dan Carpenter
2024-Jun-17 09:33 UTC
[PATCH] drm/nouveau: Use kmemdup_array() instead of kmemdup()
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.
Signed-off-by: Dan Carpenter <dan.carpenter at linaro.org>
---
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;
}
@@ -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;
--
2.43.0
Danilo Krummrich
2024-Jun-17 15:55 UTC
[PATCH] drm/nouveau: Use kmemdup_array() instead of kmemdup()
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 at linaro.org> > --- > 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;