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authorArnaldo Carvalho de Melo <acme@redhat.com>2016-03-14 09:56:35 -0300
committerZefan Li <lizefan@huawei.com>2016-10-26 23:15:47 +0800
commit887cbce4a7f533aef33da6747aaf63b54a814cc1 (patch)
treede2f03e2193ec4211f48c0bc4637611bc844e0bd
parent1c8544a93151329be95f702f6f4029f860b77ee7 (diff)
net: Fix use after free in the recvmmsg exit path
commit 34b88a68f26a75e4fded796f1a49c40f82234b7d upstream. The syzkaller fuzzer hit the following use-after-free: Call Trace: [<ffffffff8175ea0e>] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:295 [<ffffffff851cc31a>] __sys_recvmmsg+0x6fa/0x7f0 net/socket.c:2261 [< inline >] SYSC_recvmmsg net/socket.c:2281 [<ffffffff851cc57f>] SyS_recvmmsg+0x16f/0x180 net/socket.c:2270 [<ffffffff86332bb6>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 And, as Dmitry rightly assessed, that is because we can drop the reference and then touch it when the underlying recvmsg calls return some packets and then hit an error, which will make recvmmsg to set sock->sk->sk_err, oops, fix it. Reported-and-Tested-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Fixes: a2e2725541fa ("net: Introduce recvmmsg socket syscall") http://lkml.kernel.org/r/20160122211644.GC2470@redhat.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Zefan Li <lizefan@huawei.com>
-rw-r--r--net/socket.c38
1 files changed, 19 insertions, 19 deletions
diff --git a/net/socket.c b/net/socket.c
index f5ce151e0e3b..1769abc1dd55 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2332,31 +2332,31 @@ int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
break;
}
-out_put:
- fput_light(sock->file, fput_needed);
-
if (err == 0)
- return datagrams;
+ goto out_put;
- if (datagrams != 0) {
+ if (datagrams == 0) {
+ datagrams = err;
+ goto out_put;
+ }
+
+ /*
+ * We may return less entries than requested (vlen) if the
+ * sock is non block and there aren't enough datagrams...
+ */
+ if (err != -EAGAIN) {
/*
- * We may return less entries than requested (vlen) if the
- * sock is non block and there aren't enough datagrams...
+ * ... or if recvmsg returns an error after we
+ * received some datagrams, where we record the
+ * error to return on the next call or if the
+ * app asks about it using getsockopt(SO_ERROR).
*/
- if (err != -EAGAIN) {
- /*
- * ... or if recvmsg returns an error after we
- * received some datagrams, where we record the
- * error to return on the next call or if the
- * app asks about it using getsockopt(SO_ERROR).
- */
- sock->sk->sk_err = -err;
- }
-
- return datagrams;
+ sock->sk->sk_err = -err;
}
+out_put:
+ fput_light(sock->file, fput_needed);
- return err;
+ return datagrams;
}
SYSCALL_DEFINE5(recvmmsg, int, fd, struct mmsghdr __user *, mmsg,