Re: [PATCH net v2] qlcnic: prevent ->dcb use-after-free on qlcnic_dcb_enable() failure

[Michal Swiatkowski <michal.swiatkowski@linux.intel.com>]

On Thu, Dec 22, 2022 at 10:42:23AM +0300, Daniil Tatianin wrote:
> adapter->dcb would get silently freed inside qlcnic_dcb_enable() in
> case qlcnic_dcb_attach() would return an error, which always happens
> under OOM conditions. This would lead to use-after-free because both
> of the existing callers invoke qlcnic_dcb_get_info() on the obtained
> pointer, which is potentially freed at that point.
> 
> Propagate errors from qlcnic_dcb_enable(), and instead free the dcb
> pointer at callsite using qlcnic_dcb_free(). This also removes the now
> unused qlcnic_clear_dcb_ops() helper, which was a simple wrapper around
> kfree() also causing memory leaks for partially initialized dcb.
> 
> Found by Linux Verification Center (linuxtesting.org) with the SVACE
> static analysis tool.
> 
> Fixes: 3c44bba1d270 ("qlcnic: Disable DCB operations from SR-IOV VFs")
> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
> ---
> Changes since v1:
> - Add a fixes tag + net as a target
> - Remove qlcnic_clear_dcb_ops entirely & use qlcnic_dcb_free instead
> ---
>  drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c |  9 ++++++++-
>  drivers/net/ethernet/qlogic/qlcnic/qlcnic_dcb.h       | 10 ++--------
>  drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c      |  9 ++++++++-
>  3 files changed, 18 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> index dbb800769cb6..774f2c6875ec 100644
> --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_init.c
> @@ -2505,7 +2505,14 @@ int qlcnic_83xx_init(struct qlcnic_adapter *adapter)
>  		goto disable_mbx_intr;
>  
>  	qlcnic_83xx_clear_function_resources(adapter);
> -	qlcnic_dcb_enable(adapter->dcb);
> +
> +	err = qlcnic_dcb_enable(adapter->dcb);
> +	if (err) {
> +		qlcnic_dcb_free(adapter->dcb);
> +		adapter->dcb = NULL;
Small nit, I think qlcnic_dcb_free() already set adapter->dcb to NULL.

Otherwise, thanks for changing:
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>

Thanks,
Michal

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> 2.25.1