Re: [PATCH nft] rule: memleak in __do_add_setelems()

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Thu, Apr 30, 2020 at 03:52:17PM +0200, Phil Sutter wrote:
> Hi Pablo,
> 
> On Thu, Apr 30, 2020 at 03:08:20PM +0200, Pablo Neira Ayuso wrote:
> > On Thu, Apr 30, 2020 at 02:18:45PM +0200, Pablo Neira Ayuso wrote:
> > > This patch invokes interval_map_decompose() with named sets:
> > > 
> > > ==3402== 2,352 (128 direct, 2,224 indirect) bytes in 1 blocks are definitely lost in loss record 9 of 9
> > > ==3402==    at 0x483577F: malloc (vg_replace_malloc.c:299)
> > > ==3402==    by 0x48996A8: xmalloc (utils.c:36)
> > > ==3402==    by 0x4899778: xzalloc (utils.c:65)
> > > ==3402==    by 0x487CB46: expr_alloc (expression.c:45)
> > > ==3402==    by 0x487E2A0: mapping_expr_alloc (expression.c:1140)
> > > ==3402==    by 0x4898AA8: interval_map_decompose (segtree.c:1095)
> > > ==3402==    by 0x4872BDF: __do_add_setelems (rule.c:1569)
> > > ==3402==    by 0x4872BDF: __do_add_setelems (rule.c:1559)
> > > ==3402==    by 0x4877936: do_command (rule.c:2710)
> > > ==3402==    by 0x489F1CB: nft_netlink.isra.5 (libnftables.c:42)
> > > ==3402==    by 0x489FB07: nft_run_cmd_from_filename (libnftables.c:508)
> > > ==3402==    by 0x10A9AA: main (main.c:455)
> > > 
> > > Fixes: dd44081d91ce ("segtree: Fix add and delete of element in same batch")
> > 
> > This fixes the problem for anonymous sets, still named sets are
> > showing a memleak.
> 
> The change is strange: My fix (dd44081d91ce) was about anonymous sets.

It was about named sets, right?

# nft 'add element t s { 22-25 }; delete element t s { 22-25 }'

I think the cache update is still not needed for anonymous sets, even
if this was not the right fix indeed.

> Since you make the added code apply to non-anonymous sets only, I would
> expect for my testcase to start failing again (I didn't test it,
> though).
> 
> Are we maybe missing a free() somewhere instead?

I think I found the root cause:

https://marc.info/?l=netfilter-devel&m=158825784609307&w=2