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netlink: Don't shift with UB on nlk->ngroups 

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: 7acf9d4237 ("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>
This commit is contained in:
Dmitry Safonov 2018-07-30 18:32:36 +01:00 committed by David S. Miller
parent af87f72e75
commit 61f4b23769
1 changed files with 5 additions and 1 deletions
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6
net/netlink/af_netlink.c
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@ -1008,7 +1008,11 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
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) {