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Subject[PATCH 4.19 01/57] mld: fix memory leak in mld_del_delrec()
Date
From: Eric Dumazet <edumazet@google.com>

[ Upstream commit a84d016479896b5526a2cc54784e6ffc41c9d6f6 ]

Similar to the fix done for IPv4 in commit e5b1c6c6277d
("igmp: fix memory leak in igmpv3_del_delrec()"), we need to
make sure mca_tomb and mca_sources are not blindly overwritten.

Using swap() then a call to ip6_mc_clear_src() will take care
of the missing free.

BUG: memory leak
unreferenced object 0xffff888117d9db00 (size 64):
comm "syz-executor247", pid 6918, jiffies 4294943989 (age 25.350s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 fe 88 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<000000005b463030>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
[<000000005b463030>] slab_post_alloc_hook mm/slab.h:522 [inline]
[<000000005b463030>] slab_alloc mm/slab.c:3319 [inline]
[<000000005b463030>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
[<00000000939cbf94>] kmalloc include/linux/slab.h:552 [inline]
[<00000000939cbf94>] kzalloc include/linux/slab.h:748 [inline]
[<00000000939cbf94>] ip6_mc_add1_src net/ipv6/mcast.c:2236 [inline]
[<00000000939cbf94>] ip6_mc_add_src+0x31f/0x420 net/ipv6/mcast.c:2356
[<00000000d8972221>] ip6_mc_source+0x4a8/0x600 net/ipv6/mcast.c:449
[<000000002b203d0d>] do_ipv6_setsockopt.isra.0+0x1b92/0x1dd0 net/ipv6/ipv6_sockglue.c:748
[<000000001f1e2d54>] ipv6_setsockopt+0x89/0xd0 net/ipv6/ipv6_sockglue.c:944
[<00000000c8f7bdf9>] udpv6_setsockopt+0x4e/0x90 net/ipv6/udp.c:1558
[<000000005a9a0c5e>] sock_common_setsockopt+0x38/0x50 net/core/sock.c:3139
[<00000000910b37b2>] __sys_setsockopt+0x10f/0x220 net/socket.c:2084
[<00000000e9108023>] __do_sys_setsockopt net/socket.c:2100 [inline]
[<00000000e9108023>] __se_sys_setsockopt net/socket.c:2097 [inline]
[<00000000e9108023>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2097
[<00000000f4818160>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:296
[<000000008d367e8f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 1666d49e1d41 ("mld: do not remove mld souce list info when set link down")
Fixes: 9c8bb163ae78 ("igmp, mld: Fix memory leak in igmpv3/mld_del_delrec()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/mcast.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -791,14 +791,15 @@ static void mld_del_delrec(struct inet6_
if (pmc) {
im->idev = pmc->idev;
if (im->mca_sfmode == MCAST_INCLUDE) {
- im->mca_tomb = pmc->mca_tomb;
- im->mca_sources = pmc->mca_sources;
+ swap(im->mca_tomb, pmc->mca_tomb);
+ swap(im->mca_sources, pmc->mca_sources);
for (psf = im->mca_sources; psf; psf = psf->sf_next)
psf->sf_crcount = idev->mc_qrv;
} else {
im->mca_crcount = idev->mc_qrv;
}
in6_dev_put(pmc->idev);
+ ip6_mc_clear_src(pmc);
kfree(pmc);
}
spin_unlock_bh(&im->mca_lock);

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