Hi,

On 2022/12/8 11:22, Chen Zhongjin wrote:

syzkaller reported a memleak: https://syzkaller.appspot.com/bug?id=e061e6cd46417ee6566dc249d8f982c0b5977a5...

unreferenced object 0xffff888107813900 (size 256): backtrace: kcalloc include/linux/slab.h:636 [inline] tcf_exts_init include/net/pkt_cls.h:250 [inline] tcindex_set_parms+0xa7/0xbe0 net/sched/cls_tcindex.c:342 tcindex_change+0xdf/0x120 net/sched/cls_tcindex.c:553 tc_new_tfilter+0x4f2/0x1100 net/sched/cls_api.c:2147 ...

The reproduce calls tc_new_tfilter() continuously:

tc_new_tfilter()... tcindex_set_parms() tcf_exts_init(&e, ...) // alloc e->actions tcf_exts_change(&r->exts, &e)

tc_new_tfilter()... tcindex_set_parms() old_r = r // same as first r tcindex_filter_result_init(old_r, cp, net); // old_r is holding e->actions but here it calls memset(old_r, 0) // so the previous e->actions is leaked

So here tcf_exts_destroy() should be called to free old_r->exts.actions before memset(old_r, 0) sets it to NULL.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reported-by: syzbot+2f9183cb6f89b0e16586@syzkaller.appspotmail.com Signed-off-by: Chen Zhongjin chenzhongjin@huawei.com

---

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 355479c70a48

net/sched/cls_tcindex.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c index 1c9eeb98d826..00a6c04a4b42 100644 --- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -479,6 +479,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, } if (old_r && old_r != r) {

• tcf_exts_destroy(&old_r->exts);
  

  err = tcindex_filter_result_init(old_r, cp, net); if (err < 0) { kfree(f);

Just noticed that Hawkins has sent a patch for this. Please ignore mine.

Thanks!