• Davide Caratti's avatar
    net/sched: fix idr leak in the error path of tcf_skbmod_init() · bf922554
    Davide Caratti authored
    [ Upstream commit f29cdfbe33d6915ba8056179b0041279a67e3647 ]
    
    tcf_skbmod_init() can fail after the idr has been successfully reserved.
    When this happens, every subsequent attempt to configure skbmod rules
    using the same idr value will systematically fail with -ENOSPC, unless
    the first attempt was done using the 'replace' keyword:
    
     # tc action add action skbmod swap mac index 100
     RTNETLINK answers: Cannot allocate memory
     We have an error talking to the kernel
     # tc action add action skbmod swap mac index 100
     RTNETLINK answers: No space left on device
     We have an error talking to the kernel
     # tc action add action skbmod swap mac index 100
     RTNETLINK answers: No space left on device
     We have an error talking to the kernel
     ...
    
    Fix this in tcf_skbmod_init(), ensuring that tcf_idr_release() is called
    on the error path when the idr has been reserved, but not yet inserted.
    Also, don't test 'ovr' in the error path, to avoid a 'replace' failure
    implicitly become a 'delete' that leaks refcount in act_skbmod module:
    
     # rmmod act_skbmod; modprobe act_skbmod
     # tc action add action skbmod swap mac index 100
     # tc action add action skbmod swap mac continue index 100
     RTNETLINK answers: File exists
     We have an error talking to the kernel
     # tc action replace action skbmod swap mac continue index 100
     RTNETLINK answers: Cannot allocate memory
     We have an error talking to the kernel
     # tc action list action skbmod
     #
     # rmmod  act_skbmod
     rmmod: ERROR: Module act_skbmod is in use
    
    Fixes: 65a206c0 ("net/sched: Change act_api and act_xxx modules to use IDR")
    Acked-by: 's avatarJamal Hadi Salim <jhs@mojatatu.com>
    Signed-off-by: 's avatarDavide Caratti <dcaratti@redhat.com>
    Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: 's avatarSasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    bf922554