bnxt_en: make bnxt_free_skbs() safe to call after bnxt_free_mem()

stable inclusion
from stable-5.10.68
commit 0511d099db6f92680dc4f780d27492211454a02a
bugzilla: 182671 https://gitee.com/openeuler/kernel/issues/I4EWUH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0511d099db6f92680dc4f780d27492211454a02a



--------------------------------

commit 1affc01f upstream.

The call to bnxt_free_mem(..., false) in the bnxt_half_open_nic() error
path will deallocate ring descriptor memory via bnxt_free_?x_rings(),
but because irq_re_init is false, the ring info itself is not freed.

To simplify error paths, deallocation functions have generally been
written to be safe when called on unallocated memory. It should always
be safe to call dev_close(), which calls bnxt_free_skbs() a second time,
even in this semi- allocated ring state.

Calling bnxt_free_skbs() a second time with the rings already freed will
cause NULL pointer dereference.  Fix it by checking the rings are valid
before proceeding in bnxt_free_tx_skbs() and
bnxt_free_one_rx_ring_skbs().

Fixes: 975bc99a ("bnxt_en: Refactor bnxt_free_rx_skbs().")
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>