lkml.org 
[lkml]   [2019]   [Feb]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] drm/vgem: fix use-after-free when drm_gem_handle_create() fails
Date
From: Eric Biggers <ebiggers@google.com>

If drm_gem_handle_create() fails in vgem_gem_create(), then the
drm_vgem_gem_object is freed twice: once when the reference is dropped
by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().

This was hit by syzkaller using fault injection.

Fix it by skipping the second free.

Reported-by: syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com
Fixes: 5ba6c9ff961a ("drm/vgem: Fix mmaping")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
drivers/gpu/drm/vgem/vgem_drv.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 5930facd6d2d8..70646d9da1596 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -189,15 +189,13 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
return ERR_CAST(obj);

ret = drm_gem_handle_create(file, &obj->base, handle);
+
drm_gem_object_put_unlocked(&obj->base);
+
if (ret)
- goto err;
+ return ERR_PTR(ret);

return &obj->base;
-
-err:
- __vgem_gem_destroy(obj);
- return ERR_PTR(ret);
}

static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
--
2.21.0.rc2.261.ga7da99ff1b-goog
\
 
 \ /
  Last update: 2019-02-26 21:50    [W:0.085 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site