Message ID | 20190409102809.21177-2-andrea.righi@canonical.com |
---|---|
State | New |
Headers | show |
Series | openvswitch: fix kernel buffer overflow | expand |
On Tue, 9 Apr 2019 12:28:09 +0200 Andrea Righi <andrea.righi@canonical.com> wrote: > Buglink: https://bugs.launchpad.net/bugs/1813244 > > The flow action buffer can be resized if it's not big enough to contain > all the requested flow actions. However, this resize doesn't take into > account the new requested size, the buffer is only increased by a factor > of 2x. This might be not enough to contain the new data, causing a > buffer overflow, for example: > > [ 42.044472] ============================================================================= > [ 42.045608] BUG kmalloc-96 (Not tainted): Redzone overwritten > [ 42.046415] ----------------------------------------------------------------------------- > > [ 42.047715] Disabling lock debugging due to kernel taint > [ 42.047716] INFO: 0x8bf2c4a5-0x720c0928. First byte 0x0 instead of 0xcc > [ 42.048677] INFO: Slab 0xbc6d2040 objects=29 used=18 fp=0xdc07dec4 flags=0x2808101 > [ 42.049743] INFO: Object 0xd53a3464 @offset=2528 fp=0xccdcdebb > > [ 42.050747] Redzone 76f1b237: cc cc cc cc cc cc cc cc ........ > [ 42.051839] Object d53a3464: 6b 6b 6b 6b 6b 6b 6b 6b 0c 00 00 00 6c 00 00 00 kkkkkkkk....l... > [ 42.053015] Object f49a30cc: 6c 00 0c 00 00 00 00 00 00 00 00 03 78 a3 15 f6 l...........x... > [ 42.054203] Object acfe4220: 20 00 02 00 ff ff ff ff 00 00 00 00 00 00 00 00 ............... > [ 42.055370] Object 21024e91: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > [ 42.056541] Object 070e04c3: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > [ 42.057797] Object 948a777a: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > [ 42.059061] Redzone 8bf2c4a5: 00 00 00 00 .... > [ 42.060189] Padding a681b46e: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ > > Fix by making sure the new buffer is properly resized to contain all the > requested data. > > BugLink: https://bugs.launchpad.net/bugs/1813244 > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> > Acked-by: Pravin B Shelar <pshelar@ovn.org> > Signed-off-by: David S. Miller <davem@davemloft.net> > (backported from commit f28cd2af22a0c134e4aa1c64a70f70d815d473fb) The patch actually cherry picks cleanly so this should be changed to: (cherry picked from commit f28cd2af22a0c134e4aa1c64a70f70d815d473fb) > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> Acked-by: Juerg Haefliger <juergh@canonical.com> > --- > net/openvswitch/flow_netlink.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c > index 2bc1bc1aca3b..7ac03e1a799a 100644 > --- a/net/openvswitch/flow_netlink.c > +++ b/net/openvswitch/flow_netlink.c > @@ -1149,14 +1149,14 @@ static struct nlattr *reserve_sfa_size(struct sw_flow_actions **sfa, > > struct sw_flow_actions *acts; > int new_acts_size; > - int req_size = NLA_ALIGN(attr_len); > + size_t req_size = NLA_ALIGN(attr_len); > int next_offset = offsetof(struct sw_flow_actions, actions) + > (*sfa)->actions_len; > > if (req_size <= (ksize(*sfa) - next_offset)) > goto out; > > - new_acts_size = ksize(*sfa) * 2; > + new_acts_size = max(next_offset + req_size, ksize(*sfa) * 2); > > if (new_acts_size > MAX_ACTIONS_BUFSIZE) { > if ((MAX_ACTIONS_BUFSIZE - next_offset) < req_size)
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c index 2bc1bc1aca3b..7ac03e1a799a 100644 --- a/net/openvswitch/flow_netlink.c +++ b/net/openvswitch/flow_netlink.c @@ -1149,14 +1149,14 @@ static struct nlattr *reserve_sfa_size(struct sw_flow_actions **sfa, struct sw_flow_actions *acts; int new_acts_size; - int req_size = NLA_ALIGN(attr_len); + size_t req_size = NLA_ALIGN(attr_len); int next_offset = offsetof(struct sw_flow_actions, actions) + (*sfa)->actions_len; if (req_size <= (ksize(*sfa) - next_offset)) goto out; - new_acts_size = ksize(*sfa) * 2; + new_acts_size = max(next_offset + req_size, ksize(*sfa) * 2); if (new_acts_size > MAX_ACTIONS_BUFSIZE) { if ((MAX_ACTIONS_BUFSIZE - next_offset) < req_size)