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Subject[PATCH 4.14 283/496] net/sched: fix idr leak in the error path of __tcf_ipt_init()
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Davide Caratti <dcaratti@redhat.com>

[ Upstream commit 1e46ef1762bb2e52f0f996131a4d16ed4e9fd065 ]

__tcf_ipt_init() can fail after the idr has been successfully reserved.
When this happens, subsequent attempts to configure xt/ipt rules using
the same idr value systematically fail with -ENOSPC:

# tc action add action xt -j LOG --log-prefix test1 index 100
tablename: mangle hook: NF_IP_POST_ROUTING
target: LOG level warning prefix "test1" index 100
RTNETLINK answers: Cannot allocate memory
We have an error talking to the kernel
Command "(null)" is unknown, try "tc actions help".
# tc action add action xt -j LOG --log-prefix test1 index 100
tablename: mangle hook: NF_IP_POST_ROUTING
target: LOG level warning prefix "test1" index 100
RTNETLINK answers: No space left on device
We have an error talking to the kernel
Command "(null)" is unknown, try "tc actions help".
# tc action add action xt -j LOG --log-prefix test1 index 100
tablename: mangle hook: NF_IP_POST_ROUTING
target: LOG level warning prefix "test1" index 100
RTNETLINK answers: No space left on device
We have an error talking to the kernel
...

Fix this in the error path of __tcf_ipt_init(), calling tcf_idr_release()
in place of tcf_idr_cleanup(). Since tcf_ipt_release() can now be called
when tcfi_t is NULL, we also need to protect calls to ipt_destroy_target()
to avoid NULL pointer dereference.

Fixes: 65a206c01e8e ("net/sched: Change act_api and act_xxx modules to use IDR")
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/act_ipt.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/net/sched/act_ipt.c
+++ b/net/sched/act_ipt.c
@@ -80,9 +80,12 @@ static void ipt_destroy_target(struct xt
static void tcf_ipt_release(struct tc_action *a, int bind)
{
struct tcf_ipt *ipt = to_ipt(a);
- ipt_destroy_target(ipt->tcfi_t);
+
+ if (ipt->tcfi_t) {
+ ipt_destroy_target(ipt->tcfi_t);
+ kfree(ipt->tcfi_t);
+ }
kfree(ipt->tcfi_tname);
- kfree(ipt->tcfi_t);
}

static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
@@ -187,7 +190,7 @@ err2:
kfree(tname);
err1:
if (ret == ACT_P_CREATED)
- tcf_idr_cleanup(*a, est);
+ tcf_idr_release(*a, bind);
return err;
}


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