Messages in this thread | | | Date | Tue, 27 Jul 2021 18:27:06 +0530 | From | Anirudh Rayabharam <> | Subject | Re: [PATCH v7 2/2] firmware_loader: fix use-after-free in firmware_fallback_sysfs |
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On Mon, Jul 26, 2021 at 11:27:21AM -0700, Luis Chamberlain wrote: > On Sat, Jul 24, 2021 at 05:41:34PM +0530, Anirudh Rayabharam wrote: > > This use-after-free happens when a fw_priv object has been freed but > > hasn't been removed from the pending list (pending_fw_head). The next > > time fw_load_sysfs_fallback tries to insert into the list, it ends up > > accessing the pending_list member of the previoiusly freed fw_priv. > > > > The root cause here is that all code paths that abort the fw load > > don't delete it from the pending list. For example: > > > > _request_firmware() > > -> fw_abort_batch_reqs() > > -> fw_state_aborted() > > > > To fix this, delete the fw_priv from the list in __fw_set_state() if > > the new state is DONE or ABORTED. This way, all aborts will remove > > the fw_priv from the list. Accordingly, remove calls to list_del_init > > that were being made before calling fw_state_(aborted|done). > > > > Also, in fw_load_sysfs_fallback, don't add the fw_priv to the pending > > list if it is already aborted. Instead, just jump out and return early. > > > > Fixes: bcfbd3523f3c ("firmware: fix a double abort case with fw_load_sysfs_fallback") > > Reported-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com > > Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com > > Curious, how do you get syzbot to test this, I mean your custom tree?
Don't need a custom tree. You can send syzbot the git url of an existing tree (such as linux-next or Linus' tree) and a patch to apply on that tree before testing. This is documented here:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches
Of course, using a custom tree is also possible.
> > > Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com> > > With the changes Shua requested being made:
I'll implement Shua's suggestions and send a new version.
Thanks!
- Anirudh.
> > Acked-by: Luis Chamberlain <mcgrof@kernel.org> > > Luis
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