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tc: fix segmentation fault on gact action 

tc segfaults if gact action is used without action or index:

$ ip link add type dummy
$ tc actions add action pipe index 1
$ tc filter add dev dummy0 parent ffff: protocol ip \
  pref 10 u32 match ip src 127.0.0.2 flowid 1:10 action gact
Segmentation fault

We expect tc to fail gracefully with an error message.

This happens if gact is the last argument of the incomplete
command. In this case the "gact" action is parsed, the macro
NEXT_ARG_FWD() is executed and the next matches() crashes
because of null argv pointer.

To avoid this, simply use NEXT_ARG() instead.

With this change in place:

$ ip link add type dummy
$ tc actions add action pipe index 1
$ tc filter add dev dummy0 parent ffff: protocol ip \
  pref 10 u32 match ip src 127.0.0.2 flowid 1:10 action gact
Command line is not complete. Try option "help"

Fixes: fa49588973 ("tc: Fix binding of gact action by index.")
Reported-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
This commit is contained in:
Andrea Claudi 2019-10-01 12:32:17 +02:00 committed by Stephen Hemminger
parent 7c503d88d2
commit e047ca988f
1 changed files with 1 additions and 1 deletions
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2
tc/m_gact.c
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@ -87,7 +87,7 @@ parse_gact(struct action_util *a, int *argc_p, char ***argv_p,
return -1;
if (!matches(*argv, "gact"))
NEXT_ARG_FWD();
NEXT_ARG();
/* we're binding existing gact action to filter by index. */
if (!matches(*argv, "index"))
goto skip_args;