• Anirudh Rayabharam's avatar
    firmware_loader: fix use-after-free in firmware_fallback_sysfs · 75d95e2e
    Anirudh Rayabharam authored
    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 previously 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: bcfbd352 ("firmware: fix a double abort case with fw_load_sysfs_fallback")
    Cc: stable <stable@vger.kernel.org>
    Reported-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com
    Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com
    Reviewed-by: default avatarShuah Khan <skhan@linuxfoundation.org>
    Acked-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
    Signed-off-by: default avatarAnirudh Rayabharam <mail@anirudhrb.com>
    Link: https://lore.kernel.org/r/20210728085107.4141-3-mail@anirudhrb.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    75d95e2e
main.c 38.2 KB