Currently `struct drm_buf_desc` is defined as follows:
struct drm_buf_desc {
int count;
int size;
int low_mark;
int high_mark;
enum {
_DRM_PAGE_ALIGN = 0x01,
_DRM_AGP_BUFFER = 0x02,
_DRM_SG_BUFFER = 0x04,
_DRM_FB_BUFFER = 0x08,
_DRM_PCI_BUFFER_RO = 0x10
} flags;
unsigned long agp_start;
};
copy_one_buf() is potentially copying uninitialized kernel stack memory
to userspace, since the compiler may leave such "holes" (around `.flags`
and `.agp_start` fields) in this statically allocated structure. Prevent
it by initializing `v` with memset().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 5c7640ab6258 ("switch compat_drm_infobufs() to drm_ioctl_kernel()")
Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx>
---
Change in v2:
- Improve commit description. (Suggested by Arnd Bergmann
<arnd@xxxxxxxx>)
drivers/gpu/drm/drm_bufs.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index a0735fbc144b..f99cd4a3f951 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -1349,10 +1349,14 @@ static int copy_one_buf(void *data, int count, struct drm_buf_entry *from)
{
struct drm_buf_info *request = data;
struct drm_buf_desc __user *to = &request->list[count];
- struct drm_buf_desc v = {.count = from->buf_count,
- .size = from->buf_size,
- .low_mark = from->low_mark,
- .high_mark = from->high_mark};
+ struct drm_buf_desc v;
+
+ memset(&v, 0, sizeof(v));
+
+ v.count = from->buf_count;
+ v.size = from->buf_size;
+ v.low_mark = from->low_mark;
+ v.high_mark = from->high_mark;
if (copy_to_user(to, &v, offsetof(struct drm_buf_desc, flags)))
return -EFAULT;
--
2.25.1
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