4.4-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Safonov dima@arista.com
[ Upstream commit 61f4b23769f0cc72ae62c9a81cf08f0397d40da8 ]
On i386 nlk->ngroups might be 32 or 0. Which leads to UB, resulting in hang during boot. Check for 0 ngroups and use (unsigned long long) as a type to shift.
Fixes: 7acf9d4237c4 ("netlink: Do not subscribe to non-existent groups"). Reported-by: kernel test robot rong.a.chen@intel.com Signed-off-by: Dmitry Safonov dima@arista.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netlink/af_netlink.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -983,7 +983,11 @@ static int netlink_bind(struct socket *s if (err) return err; } - groups &= (1UL << nlk->ngroups) - 1; + + if (nlk->ngroups == 0) + groups = 0; + else + groups &= (1ULL << nlk->ngroups) - 1;
bound = nlk->bound; if (bound) {