| Message ID | a3e8cecc-77dd-4a4a-bb12-c1d6759d3efb@moroto.mountain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/nouveau: Use kmemdup_array() instead of kmemdup() | expand |
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@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;
…
> kmemdup_array() function has integer overflow checking built it. …
built-in?
Regards,
Markus
On Mon, Jun 17, 2024 at 05:55:33PM +0200, Danilo Krummrich wrote: > 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@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 > We can't change the return values. kmemdup_array() has to match kmemdup(). <-- returns NULL memdup_array_user() has to match memdup_user(). <-- returns error pointer regards, dan carpenter
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;
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@linaro.org> --- drivers/gpu/drm/nouveau/nouveau_sched.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)