4.9-stable review patch. If anyone has any objections, please let me know.
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From: Florian Westphal fw@strlen.de
commit d97ca5d714a5334aecadadf696875da40f1fbf3e upstream.
The sanity test added in ecd7918745234 can be bypassed, validation only occurs if XFRM_STATE_ESN flag is set, but rest of code doesn't care and just checks if the attribute itself is present.
So always validate. Alternative is to reject if we have the attribute without the flag but that would change abi.
Reported-by: syzbot+0ab777c27d2bb7588f73@syzkaller.appspotmail.com Cc: Mathias Krause minipli@googlemail.com Fixes: ecd7918745234 ("xfrm_user: ensure user supplied esn replay window is valid") Fixes: d8647b79c3b7e ("xfrm: Add user interface for esn and big anti-replay windows") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/xfrm/xfrm_user.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-)
--- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -121,22 +121,17 @@ static inline int verify_replay(struct x struct nlattr *rt = attrs[XFRMA_REPLAY_ESN_VAL]; struct xfrm_replay_state_esn *rs;
- if (p->flags & XFRM_STATE_ESN) { - if (!rt) - return -EINVAL; - - rs = nla_data(rt); + if (!rt) + return (p->flags & XFRM_STATE_ESN) ? -EINVAL : 0;
- if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8) - return -EINVAL; + rs = nla_data(rt);
- if (nla_len(rt) < xfrm_replay_state_esn_len(rs) && - nla_len(rt) != sizeof(*rs)) - return -EINVAL; - } + if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8) + return -EINVAL;
- if (!rt) - return 0; + if (nla_len(rt) < xfrm_replay_state_esn_len(rs) && + nla_len(rt) != sizeof(*rs)) + return -EINVAL;
/* As only ESP and AH support ESN feature. */ if ((p->id.proto != IPPROTO_ESP) && (p->id.proto != IPPROTO_AH))