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[76.119.149.155]) by smtp.gmail.com with ESMTPSA id t65sm21273750qkf.119.2020.07.28.04.53.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jul 2020 04:53:37 -0700 (PDT) From: Peilin Ye To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann Subject: [Linux-kernel-mentees] [PATCH v2] drm/bufs: Prevent kernel-infoleak in copy_one_buf() Date: Tue, 28 Jul 2020 07:52:10 -0400 Message-Id: <20200728115210.408486-1-yepeilin.cs@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200728014343.341303-1-yepeilin.cs@gmail.com> References: <20200728014343.341303-1-yepeilin.cs@gmail.com> MIME-Version: 1.0 X-Mailman-Approved-At: Tue, 28 Jul 2020 19:30:50 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , David Airlie , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel-mentees@lists.linuxfoundation.org, Peilin Ye , Dan Carpenter Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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@vger.kernel.org Fixes: 5c7640ab6258 ("switch compat_drm_infobufs() to drm_ioctl_kernel()") Suggested-by: Dan Carpenter Acked-by: Arnd Bergmann Signed-off-by: Peilin Ye --- Change in v2: - Improve commit description. (Suggested by Arnd Bergmann ) 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 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel