From: Wang Hai <wanghai38@xxxxxxxxxx>
[ Upstream commit acf20ed020ffa4d6cc8347e8d356509b95df3cbe ]
I got a null-ptr-deref report:
[drm:drm_dev_init [drm]] *ERROR* Cannot allocate anonymous inode: -12
==================================================================
BUG: KASAN: null-ptr-deref in iput+0x3c/0x4a0
...
Call Trace:
dump_stack_lvl+0x6c/0x8b
kasan_report.cold+0x64/0xdb
__asan_load8+0x69/0x90
iput+0x3c/0x4a0
drm_dev_init_release+0x39/0xb0 [drm]
drm_managed_release+0x158/0x2d0 [drm]
drm_dev_init+0x3a7/0x4c0 [drm]
__devm_drm_dev_alloc+0x55/0xd0 [drm]
mi0283qt_probe+0x8a/0x2b5 [mi0283qt]
spi_probe+0xeb/0x130
...
entry_SYSCALL_64_after_hwframe+0x44/0xae
If drm_fs_inode_new() fails in drm_dev_init(), dev->anon_inode will point
to PTR_ERR(...) instead of NULL. This will result in null-ptr-deref when
drm_fs_inode_free(dev->anon_inode) is called.
drm_dev_init()
drm_fs_inode_new() // fail, dev->anon_inode = PTR_ERR(...)
drm_managed_release()
drm_dev_init_release()
drm_fs_inode_free() // access non-existent anon_inode
Define a temp variable and assign it to dev->anon_inode if the temp
variable is not PTR_ERR.
Fixes: 2cbf7fc6718b ("drm: Use drmm_ for drm_dev_init cleanup")
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Wang Hai <wanghai38@xxxxxxxxxx>
Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20211013114139.4042207-1-wanghai38@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/drm_drv.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index cd162d406078a..006e3b896caea 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -577,6 +577,7 @@ static int drm_dev_init(struct drm_device *dev,
struct drm_driver *driver,
struct device *parent)
{
+ struct inode *inode;
int ret;
if (!drm_core_init_complete) {
@@ -613,13 +614,15 @@ static int drm_dev_init(struct drm_device *dev,
if (ret)
return ret;
- dev->anon_inode = drm_fs_inode_new();
- if (IS_ERR(dev->anon_inode)) {
- ret = PTR_ERR(dev->anon_inode);
+ inode = drm_fs_inode_new();
+ if (IS_ERR(inode)) {
+ ret = PTR_ERR(inode);
DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
goto err;
}
+ dev->anon_inode = inode;
+
if (drm_core_check_feature(dev, DRIVER_RENDER)) {
ret = drm_minor_alloc(dev, DRM_MINOR_RENDER);
if (ret)
--
2.34.1
