This is a note to let you know that I've just added the patch titled
drm/msm: fix use of copy_from_user() while holding spinlock
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-msm-fix-use-of-copy_from_user-while-holding-spinlock.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 89f82cbb0d5c0ab768c8d02914188aa2211cd2e3 Mon Sep 17 00:00:00 2001
From: Rob Clark <robdclark@xxxxxxxxx>
Date: Mon, 22 Aug 2016 15:15:23 -0400
Subject: drm/msm: fix use of copy_from_user() while holding spinlock
From: Rob Clark <robdclark@xxxxxxxxx>
commit 89f82cbb0d5c0ab768c8d02914188aa2211cd2e3 upstream.
Use instead __copy_from_user_inatomic() and fallback to slow-path where
we drop and re-aquire the lock in case of fault.
Reported-by: Vaishali Thakkar <vaishali.thakkar@xxxxxxxxxx>
Signed-off-by: Rob Clark <robdclark@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/msm/msm_gem_submit.c | 27 ++++++++++++++++++++++-----
1 file changed, 22 insertions(+), 5 deletions(-)
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -55,6 +55,14 @@ static struct msm_gem_submit *submit_cre
return submit;
}
+static inline unsigned long __must_check
+copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
+{
+ if (access_ok(VERIFY_READ, from, n))
+ return __copy_from_user_inatomic(to, from, n);
+ return -EFAULT;
+}
+
static int submit_lookup_objects(struct msm_gem_submit *submit,
struct drm_msm_gem_submit *args, struct drm_file *file)
{
@@ -62,6 +70,7 @@ static int submit_lookup_objects(struct
int ret = 0;
spin_lock(&file->table_lock);
+ pagefault_disable();
for (i = 0; i < args->nr_bos; i++) {
struct drm_msm_gem_submit_bo submit_bo;
@@ -70,10 +79,15 @@ static int submit_lookup_objects(struct
void __user *userptr =
to_user_ptr(args->bos + (i * sizeof(submit_bo)));
- ret = copy_from_user(&submit_bo, userptr, sizeof(submit_bo));
- if (ret) {
- ret = -EFAULT;
- goto out_unlock;
+ ret = copy_from_user_inatomic(&submit_bo, userptr, sizeof(submit_bo));
+ if (unlikely(ret)) {
+ pagefault_enable();
+ spin_unlock(&file->table_lock);
+ ret = copy_from_user(&submit_bo, userptr, sizeof(submit_bo));
+ if (ret)
+ goto out;
+ spin_lock(&file->table_lock);
+ pagefault_disable();
}
if (submit_bo.flags & ~MSM_SUBMIT_BO_FLAGS) {
@@ -113,9 +127,12 @@ static int submit_lookup_objects(struct
}
out_unlock:
- submit->nr_bos = i;
+ pagefault_enable();
spin_unlock(&file->table_lock);
+out:
+ submit->nr_bos = i;
+
return ret;
}
Patches currently in stable-queue which might be from robdclark@xxxxxxxxx are
queue-4.4/drm-msm-fix-use-of-copy_from_user-while-holding-spinlock.patch
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