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SubjectRe: [RFC] igmp: address pmc kmemleak from on igmpv3_del_delrec()
On Fri, Feb 3, 2017 at 1:20 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> When we igmpv3_add_delrec() we kzalloc the pmc, but when users
> call igmpv3_del_delrec() we never free the pmc. This was caught
> by the following kmemleak splat:
>
> unreferenced object 0xffff99666ff43b40 (size 192):
> comm "systemd-resolve", pid 1258, jiffies 4309905600 (age 2138.352s)
> hex dump (first 32 bytes):
> 00 6a 64 72 66 99 ff ff e0 00 00 fc 00 00 00 00 .jdrf...........
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<ffffffffb3a5f7ea>] kmemleak_alloc+0x4a/0xa0
> [<ffffffffb36044e7>] kmem_cache_alloc_trace+0x107/0x240
> [<ffffffffb39ddbed>] igmp_group_dropped+0xfd/0x270
> [<ffffffffb39de5cf>] ip_mc_dec_group+0xaf/0x110
> [<ffffffffb39de6e6>] ip_mc_leave_group+0xb6/0x140
> [<ffffffffb39a55d7>] do_ip_setsockopt.isra.13+0x4c7/0xed0
> [<ffffffffb39a6014>] ip_setsockopt+0x34/0xb0
> [<ffffffffb39ced9b>] udp_setsockopt+0x1b/0x30
> [<ffffffffb393f064>] sock_common_setsockopt+0x14/0x20
> [<ffffffffb393dd10>] SyS_setsockopt+0x80/0xe0
> [<ffffffffb3403b4b>] do_syscall_64+0x5b/0xc0
> [<ffffffffb3a6b3af>] return_from_SYSCALL_64+0x0/0x6a
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
>
> I can reproduce this over time on a qemu box running next-20170125.
> After running this for a while I no longer see the splat. This needs
> confirmation form folks more familiar with the code, hence RFC. If
> this is a real fix we need appropriate tags for the patch.


Looks good to me. Adding some people who recent touched it to CC.

>
> net/ipv4/igmp.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 5b15459955f8..44fd86de2823 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -1172,6 +1172,7 @@ static void igmpv3_del_delrec(struct in_device *in_dev, struct ip_mc_list *im)
> psf->sf_crcount = im->crcount;
> }
> in_dev_put(pmc->interface);
> + kfree(pmc);
> }
> spin_unlock_bh(&im->lock);
> }
> --
> 2.11.0
>

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