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Commit a1b37f12 authored by lifr's avatar lifr Committed by Frank Li
Browse files

Fix hwasan stack buffer overflow in resolver stats 

This change will handle netdID unknown case to avoid accessing the uninitialized
local variable stats. If the netId is unknown (which can happen for
valid net IDs for which no DNS servers have yet been configured),
it need to return error directly instead of access the stats.
(The happening is if stats->sample_next is uninitialized or corrupted.)


Test: ./runtests.sh pass
Bug: 123593418

Change-Id: I76b8b23ff618071e3aea9d8abc8aff8887bbab88
parent 3952ccca

res_send.cpp

+5 −0
Original line number Diff line number Diff line
@@ -487,6 +487,11 @@ int res_nsend(res_state statp, const u_char* buf, int buflen, u_char* ans, int a 
    res_stats stats[MAXNS];

    res_params params;

    int revision_id = resolv_cache_get_resolver_stats(statp->netid, &params, stats);

    if (revision_id < 0) {

        // TODO: Remove errno once callers stop using it

        errno = ESRCH;

        return -ESRCH;

    }

    bool usable_servers[MAXNS];

    android_net_res_stats_get_usable_servers(&params, stats, statp->nscount, usable_servers);

    if (params.retry_count != 0) statp->retry = params.retry_count;