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drm: stop information leak of old kernel stack.

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non-critical issue, CVE-2010-2803

Userspace controls the amount of memory to be allocate, so it can
get the ioctl to allocate more memory than the kernel uses, and get
access to kernel stack. This can only be done for processes authenticated
to the X server for DRI access, and if the user has DRI access.

Fix is to just memset the data to 0 if the user doesn't copy into
it in the first place.

Reported-by: Kees Cook <kees@ubuntu.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Dave Airlie 2010-08-17 14:46:00 +10:00
parent 31ce4bfdfd
commit b9f0aee833
1 changed files with 3 additions and 1 deletions
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4
drivers/gpu/drm/drm_drv.c
View file

@ -477,7 +477,9 @@ long drm_ioctl(struct file *filp,
retcode = -EFAULT; retcode = -EFAULT;
goto err_i1; goto err_i1;
} }
} } else
memset(kdata, 0, _IOC_SIZE(cmd));
if (ioctl->flags & DRM_UNLOCKED) if (ioctl->flags & DRM_UNLOCKED)
retcode = func(dev, kdata, file_priv); retcode = func(dev, kdata, file_priv);
else { else {