From: Jakub Kicinski kuba@kernel.org
commit 249801360db3dec4f73768c502192020bfddeacc upstream.
If construction of the array of policies fails when recording non-first policy we need to unwind.
netlink_policy_dump_add_policy() itself also needs fixing as it currently gives up on error without recording the allocated pointer in the pstate pointer.
Reported-by: syzbot+dc54d9ba8153b216cae0@syzkaller.appspotmail.com Fixes: 50a896cf2d6f ("genetlink: properly support per-op policy dumping") Link: https://lore.kernel.org/r/20220816161939.577583-1-kuba@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netlink/genetlink.c | 6 +++++- net/netlink/policy.c | 14 ++++++++++++-- 2 files changed, 17 insertions(+), 3 deletions(-)
--- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -1174,13 +1174,17 @@ static int ctrl_dumppolicy_start(struct op.policy, op.maxattr); if (err) - return err; + goto err_free_state; } }
if (!ctx->state) return -ENODATA; return 0; + +err_free_state: + netlink_policy_dump_free(ctx->state); + return err; }
static void *ctrl_dumppolicy_prep(struct sk_buff *skb, --- a/net/netlink/policy.c +++ b/net/netlink/policy.c @@ -144,7 +144,7 @@ int netlink_policy_dump_add_policy(struc
err = add_policy(&state, policy, maxtype); if (err) - return err; + goto err_try_undo;
for (policy_idx = 0; policy_idx < state->n_alloc && state->policies[policy_idx].policy; @@ -164,7 +164,7 @@ int netlink_policy_dump_add_policy(struc policy[type].nested_policy, policy[type].len); if (err) - return err; + goto err_try_undo; break; default: break; @@ -174,6 +174,16 @@ int netlink_policy_dump_add_policy(struc
*pstate = state; return 0; + +err_try_undo: + /* Try to preserve reasonable unwind semantics - if we're starting from + * scratch clean up fully, otherwise record what we got and caller will. + */ + if (!*pstate) + netlink_policy_dump_free(state); + else + *pstate = state; + return err; }
static bool