diff options
author | Eric W. Biederman <ebiederm@xmission.com> | 2017-11-15 22:17:48 -0600 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-24 08:33:41 +0100 |
commit | 67b718fcf89745836ecbf15cdd46ded2b071c3b6 (patch) | |
tree | 958d1068e12e20f3663e04713372d185bfb70491 /crypto | |
parent | f0ae7a1b45fa38178e0f6fa244897e1e28601223 (diff) |
net/sctp: Always set scope_id in sctp_inet6_skb_msgname
[ Upstream commit 7c8a61d9ee1df0fb4747879fa67a99614eb62fec ]
Alexandar Potapenko while testing the kernel with KMSAN and syzkaller
discovered that in some configurations sctp would leak 4 bytes of
kernel stack.
Working with his reproducer I discovered that those 4 bytes that
are leaked is the scope id of an ipv6 address returned by recvmsg.
With a little code inspection and a shrewd guess I discovered that
sctp_inet6_skb_msgname only initializes the scope_id field for link
local ipv6 addresses to the interface index the link local address
pertains to instead of initializing the scope_id field for all ipv6
addresses.
That is almost reasonable as scope_id's are meaniningful only for link
local addresses. Set the scope_id in all other cases to 0 which is
not a valid interface index to make it clear there is nothing useful
in the scope_id field.
There should be no danger of breaking userspace as the stack leak
guaranteed that previously meaningless random data was being returned.
Fixes: 372f525b495c ("SCTP: Resync with LKSCTP tree.")
History-tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Reported-by: Alexander Potapenko <glider@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'crypto')
0 files changed, 0 insertions, 0 deletions