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| author | Harald Welte <laforge@gnumonks.org> | 2018-04-16 22:53:48 +0200 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2018-04-17 12:06:52 +0000 |
| commit | 0b2c0ecd5e283bb75765447724a9b1e26f6478b5 (patch) | |
| tree | cb104b407e37b7d34bfcae59f27480b411f7a0f7 /src | |
| parent | 62c43c6969bf81834801372a0892eaa9dabb67a3 (diff) | |
prevent integer underflow in ipa_ccm_make_id_resp_from_req()
don't blindly trust the tag-length value in an IPA CCM ID GET
message. This could result in a remotely-triggered integer underflow.
Change-Id: I4723361e1094b358310541a7dc4c5c921c778a15
Diffstat (limited to 'src')
| -rw-r--r-- | src/gsm/ipa.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/gsm/ipa.c b/src/gsm/ipa.c index e03f6153..0c7aaad6 100644 --- a/src/gsm/ipa.c +++ b/src/gsm/ipa.c @@ -328,7 +328,12 @@ struct msgb *ipa_ccm_make_id_resp_from_req(const struct ipaccess_unit *dev, ies[num_ies++] = t_tag; cur += t_len; - len -= t_len; + /* prevent any unsigned integer underflow due to somebody sending us + * messages with wrong length values */ + if (len <= t_len) + len -= t_len; + else + len = 0; } return ipa_ccm_make_id_resp(dev, ies, num_ies); } |