Messages in this thread | | | Date | Tue, 07 Aug 2018 15:41:41 -0700 | From | rishabhb@codeauro ... | Subject | Re: [PATCH] firmware: Fix security issue with request_firmware_into_buf() |
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On 2018-08-02 14:58, Luis Chamberlain wrote: > On Wed, Aug 1, 2018, 4:26 PM Rishabh Bhatnagar > <rishabhb@codeaurora.org> wrote: > >> When calling request_firmware_into_buf() with the FW_OPT_NOCACHE >> flag >> it is expected that firmware is loaded into buffer from memory. >> But inside alloc_lookup_fw_priv every new firmware that is loaded is >> added to the firmware cache (fwc) list head. So if any driver >> requests >> a firmware that is already loaded the code iterates over the above >> mentioned list and it can end up giving a pointer to other device >> driver's >> firmware buffer. >> Also the existing copy may either be modified by drivers, remote >> processors >> or even freed. This causes a potential security issue with batched >> requests >> when using request_firmware_into_buf. >> >> Fix alloc_lookup_fw_priv to not add to the fwc head list if >> FW_OPT_NOCACHE >> is set, and also don't do the lookup in the list. >> >> Fixes: 0e742e9275 ("firmware: provide infrastructure to make fw >> caching optional") >> >> Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> >> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org> >> --- > > Did you test with the tools/testing/selftests/firmware/ scripts? If > not please do so and report back and confirm no regressions are found. > > Brownie points for you to add a test case to show the issue > highlighted in this patch, and which it fixes. I believe this fix > should be pushed to stable, so I'll do that after you confirm no > regressions were found. > > The new selftests changed you'd make would not go to stable, however > there are Linux distributions and 0day that test the latest tools > directory against older kernels. So this test would help capture gaps > later. > > Luis
I ran the selftests and observed no regressions with this change. I'm still working on adding a test case though.
-Rishabh
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