From: "Christian König" <christian.koenig@amd.com> To: cuigaosheng <cuigaosheng1@huawei.com>, Charan Teja Kalla <quic_charante@quicinc.com>, "T.J. Mercier" <tjmercier@google.com> Cc: sumit.semwal@linaro.org, Dan Carpenter <dan.carpenter@oracle.com>, Pavan Kondeti <quic_pkondeti@quicinc.com>, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org Subject: Re: [PATCH] dma-buf: Fix possible UAF in dma_buf_export Date: Thu, 24 Nov 2022 13:37:41 +0100 [thread overview] Message-ID: <689ad89b-0e34-3743-24c9-3f92856720f8@amd.com> (raw) In-Reply-To: <b2d5d904-99f2-7974-a22d-63a6cf864973@huawei.com> Am 24.11.22 um 13:05 schrieb cuigaosheng: > Some tips: > Before we call the dma_buf_stats_setup(), we have to finish > creating the file, > otherwise dma_buf_stats_setup() will return -EINVAL, maybe we need to > think about > this when making a new patch. I was already wondering why the order is this way. Why is dma_buf_stats_setup() needing the file in the first place? Thanks, Christian. > > Hope these tips are useful, thanks! > > On 2022/11/24 13:56, Charan Teja Kalla wrote: >> Thanks T.J and Christian for the inputs. >> >> On 11/19/2022 7:00 PM, Christian König wrote: >>>> Yes, exactly that's the idea. >>>> >>>> The only alternatives I can see would be to either move >>>> allocating >>>> the >>>> file and so completing the dma_buf initialization last again >>>> or just >>>> ignore errors from sysfs. >>>> >>>> > If we still want to avoid calling >>>> dmabuf->ops->release(dmabuf) in >>>> > dma_buf_release like the comment says I guess we could use >>>> sysfs_entry >>>> > and ERR_PTR to flag that, otherwise it looks like we'd need >>>> a bit >>>> > somewhere. >>>> >>>> No, this should be dropped as far as I can see. The sysfs cleanup >>>> code >>>> looks like it can handle not initialized kobj pointers. >>>> >>>> >>>> Yeah there is also the null check in dma_buf_stats_teardown() that >>>> would prevent it from running, but I understood the comment to be >>>> referring to the release() dma_buf_ops call into the exporter which >>>> comes right after the teardown call. That looks like it's preventing >>>> the fput task work calling back into the exporter after the exporter >>>> already got an error from dma_buf_export(). Otherwise the exporter >>>> sees a release() for a buffer that it doesn't know about / thinks >>>> shouldn't exist. So I could imagine an exporter trying to double free: >>>> once for the failed dma_buf_export() call, and again when the >>>> release() op is called later. >>> >>> Oh, very good point as well. Yeah, then creating the file should >>> probably come last. >>> >> @Gaosheng: Could you please make these changes or you let me to do? >> >>> Regards, >>> Christian. >> .
WARNING: multiple messages have this Message-ID (diff)
From: "Christian König" <christian.koenig@amd.com> To: cuigaosheng <cuigaosheng1@huawei.com>, Charan Teja Kalla <quic_charante@quicinc.com>, "T.J. Mercier" <tjmercier@google.com> Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, sumit.semwal@linaro.org, Dan Carpenter <dan.carpenter@oracle.com>, linux-media@vger.kernel.org Subject: Re: [PATCH] dma-buf: Fix possible UAF in dma_buf_export Date: Thu, 24 Nov 2022 13:37:41 +0100 [thread overview] Message-ID: <689ad89b-0e34-3743-24c9-3f92856720f8@amd.com> (raw) In-Reply-To: <b2d5d904-99f2-7974-a22d-63a6cf864973@huawei.com> Am 24.11.22 um 13:05 schrieb cuigaosheng: > Some tips: > Before we call the dma_buf_stats_setup(), we have to finish > creating the file, > otherwise dma_buf_stats_setup() will return -EINVAL, maybe we need to > think about > this when making a new patch. I was already wondering why the order is this way. Why is dma_buf_stats_setup() needing the file in the first place? Thanks, Christian. > > Hope these tips are useful, thanks! > > On 2022/11/24 13:56, Charan Teja Kalla wrote: >> Thanks T.J and Christian for the inputs. >> >> On 11/19/2022 7:00 PM, Christian König wrote: >>>> Yes, exactly that's the idea. >>>> >>>> The only alternatives I can see would be to either move >>>> allocating >>>> the >>>> file and so completing the dma_buf initialization last again >>>> or just >>>> ignore errors from sysfs. >>>> >>>> > If we still want to avoid calling >>>> dmabuf->ops->release(dmabuf) in >>>> > dma_buf_release like the comment says I guess we could use >>>> sysfs_entry >>>> > and ERR_PTR to flag that, otherwise it looks like we'd need >>>> a bit >>>> > somewhere. >>>> >>>> No, this should be dropped as far as I can see. The sysfs cleanup >>>> code >>>> looks like it can handle not initialized kobj pointers. >>>> >>>> >>>> Yeah there is also the null check in dma_buf_stats_teardown() that >>>> would prevent it from running, but I understood the comment to be >>>> referring to the release() dma_buf_ops call into the exporter which >>>> comes right after the teardown call. That looks like it's preventing >>>> the fput task work calling back into the exporter after the exporter >>>> already got an error from dma_buf_export(). Otherwise the exporter >>>> sees a release() for a buffer that it doesn't know about / thinks >>>> shouldn't exist. So I could imagine an exporter trying to double free: >>>> once for the failed dma_buf_export() call, and again when the >>>> release() op is called later. >>> >>> Oh, very good point as well. Yeah, then creating the file should >>> probably come last. >>> >> @Gaosheng: Could you please make these changes or you let me to do? >> >>> Regards, >>> Christian. >> .
next prev parent reply other threads:[~2022-11-24 12:37 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-17 6:21 [PATCH] dma-buf: Fix possible UAF in dma_buf_export Gaosheng Cui 2022-11-17 6:21 ` Gaosheng Cui 2022-11-17 7:48 ` Charan Teja Kalla 2022-11-17 7:48 ` Charan Teja Kalla 2022-11-17 10:16 ` Christian König 2022-11-17 10:16 ` Christian König 2022-11-18 2:36 ` T.J. Mercier 2022-11-18 2:36 ` T.J. Mercier 2022-11-18 8:27 ` Christian König 2022-11-18 8:27 ` Christian König 2022-11-18 17:05 ` T.J. Mercier 2022-11-19 13:30 ` Christian König 2022-11-24 5:56 ` Charan Teja Kalla 2022-11-24 5:56 ` Charan Teja Kalla 2022-11-24 11:31 ` cuigaosheng 2022-11-24 11:31 ` cuigaosheng 2022-11-24 12:05 ` cuigaosheng 2022-11-24 12:05 ` cuigaosheng 2022-11-24 12:37 ` Christian König [this message] 2022-11-24 12:37 ` Christian König 2022-11-24 12:49 ` cuigaosheng 2022-11-24 12:49 ` cuigaosheng 2022-11-24 12:55 ` [Linaro-mm-sig] " Christian König 2022-11-24 12:55 ` Christian König 2022-12-06 12:55 ` Charan Teja Kalla 2022-12-06 12:55 ` Charan Teja Kalla 2022-12-06 13:08 ` Christian König 2022-12-06 13:08 ` Christian König
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