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| author | Julian Wiedmann <jwi@linux.ibm.com> | 2019-08-23 11:29:23 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-08-24 16:34:08 -0700 |
| commit | 292a50e3fc2cf699587ea282e6253e0d6ae3cdc1 (patch) | |
| tree | c40d909aa89da896c06a1e1924c06c762f3f12d8 | |
| parent | b45ce32135d1c82a5bf12aa56957c3fd27956057 (diff) | |
| download | linux-292a50e3fc2cf699587ea282e6253e0d6ae3cdc1.tar.bz2 | |
s390/qeth: reject oversized SNMP requests
Commit d4c08afafa04 ("s390/qeth: streamline SNMP cmd code") removed
the bounds checking for req_len, under the assumption that the check in
qeth_alloc_cmd() would suffice.
But that code path isn't sufficiently robust to handle a user-provided
data_length, which could overflow (when adding the cmd header overhead)
before being checked against QETH_BUFSIZE. We end up allocating just a
tiny iob, and the subsequent copy_from_user() writes past the end of
that iob.
Special-case this path and add a coarse bounds check, to protect against
maliciuous requests. This let's the subsequent code flow do its normal
job and precise checking, without risk of overflow.
Fixes: d4c08afafa04 ("s390/qeth: streamline SNMP cmd code")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/s390/net/qeth_core_main.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index 9c3310c4d61d..6502b148541e 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -4374,6 +4374,10 @@ static int qeth_snmp_command(struct qeth_card *card, char __user *udata) get_user(req_len, &ureq->hdr.req_len)) return -EFAULT; + /* Sanitize user input, to avoid overflows in iob size calculation: */ + if (req_len > QETH_BUFSIZE) + return -EINVAL; + iob = qeth_get_adapter_cmd(card, IPA_SETADP_SET_SNMP_CONTROL, req_len); if (!iob) return -ENOMEM; |