ipv6: Fix out-of-bounds access in ipv6_find_tlv()

stable inclusion
from stable-v5.10.181
commit e5f82688ae10f5f386952e65e941bb8868ee54dc
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8GJZJ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e5f82688ae10f5f386952e65e941bb8868ee54dc



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commit 878ecb08 upstream.

optlen is fetched without checking whether there is more than one byte to parse.
It can lead to out-of-bounds access.

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.

Fixes: c61a4043 ("[IPV6]: Find option offset by type.")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>