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author | Dan Carpenter <dan.carpenter@oracle.com> | 2020-09-09 12:46:48 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-26 18:01:29 +0200 |
commit | 45676c0bc28eff8f46455b28e2db80a77676488b (patch) | |
tree | b378f1f8aef79c8a2b49d1299c74546aa9058ba9 /drivers/net/wan | |
parent | c797110d97c48054d1491251fd713900ff51615c (diff) | |
download | linux-stable-45676c0bc28eff8f46455b28e2db80a77676488b.tar.gz linux-stable-45676c0bc28eff8f46455b28e2db80a77676488b.tar.bz2 linux-stable-45676c0bc28eff8f46455b28e2db80a77676488b.zip |
hdlc_ppp: add range checks in ppp_cp_parse_cr()
[ Upstream commit 66d42ed8b25b64eb63111a2b8582c5afc8bf1105 ]
There are a couple bugs here:
1) If opt[1] is zero then this results in a forever loop. If the value
is less than 2 then it is invalid.
2) It assumes that "len" is more than sizeof(valid_accm) or 6 which can
result in memory corruption.
In the case of LCP_OPTION_ACCM, then we should check "opt[1]" instead
of "len" because, if "opt[1]" is less than sizeof(valid_accm) then
"nak_len" gets out of sync and it can lead to memory corruption in the
next iterations through the loop. In case of LCP_OPTION_MAGIC, the
only valid value for opt[1] is 6, but the code is trying to log invalid
data so we should only discard the data when "len" is less than 6
because that leads to a read overflow.
Reported-by: ChenNan Of Chaitin Security Research Lab <whutchennan@gmail.com>
Fixes: e022c2f07ae5 ("WAN: new synchronous PPP implementation for generic HDLC.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net/wan')
-rw-r--r-- | drivers/net/wan/hdlc_ppp.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/net/wan/hdlc_ppp.c b/drivers/net/wan/hdlc_ppp.c index ab8b3cbbb205..85844f26547d 100644 --- a/drivers/net/wan/hdlc_ppp.c +++ b/drivers/net/wan/hdlc_ppp.c @@ -386,11 +386,8 @@ static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id, } for (opt = data; len; len -= opt[1], opt += opt[1]) { - if (len < 2 || len < opt[1]) { - dev->stats.rx_errors++; - kfree(out); - return; /* bad packet, drop silently */ - } + if (len < 2 || opt[1] < 2 || len < opt[1]) + goto err_out; if (pid == PID_LCP) switch (opt[0]) { @@ -398,6 +395,8 @@ static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id, continue; /* MRU always OK and > 1500 bytes? */ case LCP_OPTION_ACCM: /* async control character map */ + if (opt[1] < sizeof(valid_accm)) + goto err_out; if (!memcmp(opt, valid_accm, sizeof(valid_accm))) continue; @@ -409,6 +408,8 @@ static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id, } break; case LCP_OPTION_MAGIC: + if (len < 6) + goto err_out; if (opt[1] != 6 || (!opt[2] && !opt[3] && !opt[4] && !opt[5])) break; /* reject invalid magic number */ @@ -427,6 +428,11 @@ static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id, ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data); kfree(out); + return; + +err_out: + dev->stats.rx_errors++; + kfree(out); } static int ppp_rx(struct sk_buff *skb) |