From: Eric Dumazet <eduma...@google.com>
Date: Thu, 27 Jun 2019 01:27:01 -0700
> im->tomb and/or im->sources might not be NULL, but we
> currently overwrite their values blindly.
>
> Using swap() will make sure the following call to kfree_pmc(pmc)
> will properly free the psf structures.
>
> Tested with the C repro provided by syzbot, which basically does :
>
> socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
> setsockopt(3, SOL_IP, IP_ADD_MEMBERSHIP, "\340\0\0\2\177\0\0\1\0\0\0\0", 12)
> = 0
> ioctl(3, SIOCSIFFLAGS, {ifr_name="lo", ifr_flags=0}) = 0
> setsockopt(3, SOL_IP, IP_MSFILTER,
> "\340\0\0\2\177\0\0\1\1\0\0\0\1\0\0\0\377\377\377\377", 20) = 0
> ioctl(3, SIOCSIFFLAGS, {ifr_name="lo", ifr_flags=IFF_UP}) = 0
> exit_group(0) = ?
>
> BUG: memory leak
> unreferenced object 0xffff88811450f140 (size 64):
...
> Fixes: 24803f38a5c0 ("igmp: do not remove igmp souce list info when set link
> down")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Cc: Hangbin Liu <liuhang...@gmail.com>
> Reported-by: syzbot+6ca1abd0db68b5173...@syzkaller.appspotmail.com
Applied and queued up for -stable, thanks.
