Eric Lee / smarc-fsl-linux-kernel

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Commit 32b2f4b196b37695fdb42b31afcbc15399d6ef91

Authored by Daniel Borkmann
Committed by David S. Miller
1 parent ff3532f265

sched: cls_flow: fix panic on filter replace 

The following test case causes a NULL pointer dereference in cls_flow:

  tc filter add dev foo parent 1: handle 0x1 flow hash keys dst action ok
  tc filter replace dev foo parent 1: pref 49152 handle 0x1 \
            flow hash keys mark action drop

To be more precise, actually two different panics are fixed, the first
occurs because tcf_exts_init() is not called on the newly allocated
filter when we do a replace. And the second panic uncovered after that
happens since the arguments of list_replace_rcu() are swapped, the old
element needs to be the first argument and the new element the second.

Fixes: 70da9f0bf999 ("net: sched: cls_flow use RCU")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Showing 1 changed file with 3 additions and 2 deletions Side-by-side Diff

net/sched/cls_flow.c
Diff comments   View file @ 32b2f4b
... ... @@ -425,6 +425,8 @@
425 425 if (!fnew)
426 426 goto err2;
427 427  
  428 + tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE);
  429 +
428 430 fold = (struct flow_filter *)*arg;
429 431 if (fold) {
430 432 err = -EINVAL;
... ... @@ -486,7 +488,6 @@
486 488 fnew->mask = ~0U;
487 489 fnew->tp = tp;
488 490 get_random_bytes(&fnew->hashrnd, 4);
489   - tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE);
490 491 }
491 492  
492 493 fnew->perturb_timer.function = flow_perturbation;
... ... @@ -526,7 +527,7 @@
526 527 if (*arg == 0)
527 528 list_add_tail_rcu(&fnew->list, &head->filters);
528 529 else
529   - list_replace_rcu(&fnew->list, &fold->list);
  530 + list_replace_rcu(&fold->list, &fnew->list);
530 531  
531 532 *arg = (unsigned long)fnew;
532 533