* [PATCH] openvswitch: fix OOB access in reserve_sfa_size()
@ 2022-04-15 8:08 Paolo Valerio
2022-04-15 10:25 ` [ovs-dev] " Eelco Chaudron
2022-04-15 11:00 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Paolo Valerio @ 2022-04-15 8:08 UTC (permalink / raw)
To: netdev, dev
Cc: Pravin B Shelar, David S. Miller, Jakub Kicinski, Paolo Abeni,
stable
Given a sufficiently large number of actions, while copying and
reserving memory for a new action of a new flow, if next_offset is
greater than MAX_ACTIONS_BUFSIZE, the function reserve_sfa_size() does
not return -EMSGSIZE as expected, but it allocates MAX_ACTIONS_BUFSIZE
bytes increasing actions_len by req_size. This can then lead to an OOB
write access, especially when further actions need to be copied.
Fix it by rearranging the flow action size check.
KASAN splat below:
==================================================================
BUG: KASAN: slab-out-of-bounds in reserve_sfa_size+0x1ba/0x380 [openvswitch]
Write of size 65360 at addr ffff888147e4001c by task handler15/836
CPU: 1 PID: 836 Comm: handler15 Not tainted 5.18.0-rc1+ #27
...
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x5a
print_report.cold+0x5e/0x5db
? __lock_text_start+0x8/0x8
? reserve_sfa_size+0x1ba/0x380 [openvswitch]
kasan_report+0xb5/0x130
? reserve_sfa_size+0x1ba/0x380 [openvswitch]
kasan_check_range+0xf5/0x1d0
memcpy+0x39/0x60
reserve_sfa_size+0x1ba/0x380 [openvswitch]
__add_action+0x24/0x120 [openvswitch]
ovs_nla_add_action+0xe/0x20 [openvswitch]
ovs_ct_copy_action+0x29d/0x1130 [openvswitch]
? __kernel_text_address+0xe/0x30
? unwind_get_return_address+0x56/0xa0
? create_prof_cpu_mask+0x20/0x20
? ovs_ct_verify+0xf0/0xf0 [openvswitch]
? prep_compound_page+0x198/0x2a0
? __kasan_check_byte+0x10/0x40
? kasan_unpoison+0x40/0x70
? ksize+0x44/0x60
? reserve_sfa_size+0x75/0x380 [openvswitch]
__ovs_nla_copy_actions+0xc26/0x2070 [openvswitch]
? __zone_watermark_ok+0x420/0x420
? validate_set.constprop.0+0xc90/0xc90 [openvswitch]
? __alloc_pages+0x1a9/0x3e0
? __alloc_pages_slowpath.constprop.0+0x1da0/0x1da0
? unwind_next_frame+0x991/0x1e40
? __mod_node_page_state+0x99/0x120
? __mod_lruvec_page_state+0x2e3/0x470
? __kasan_kmalloc_large+0x90/0xe0
ovs_nla_copy_actions+0x1b4/0x2c0 [openvswitch]
ovs_flow_cmd_new+0x3cd/0xb10 [openvswitch]
...
Cc: stable@vger.kernel.org
Fixes: f28cd2af22a0 ("openvswitch: fix flow actions reallocation")
Signed-off-by: Paolo Valerio <pvalerio@redhat.com>
---
net/openvswitch/flow_netlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 7176156d3844..4c09cf8a0ab2 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -2465,7 +2465,7 @@ static struct nlattr *reserve_sfa_size(struct sw_flow_actions **sfa,
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) {
+ if ((next_offset + req_size) > MAX_ACTIONS_BUFSIZE) {
OVS_NLERR(log, "Flow action size exceeds max %u",
MAX_ACTIONS_BUFSIZE);
return ERR_PTR(-EMSGSIZE);
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [ovs-dev] [PATCH] openvswitch: fix OOB access in reserve_sfa_size()
2022-04-15 8:08 [PATCH] openvswitch: fix OOB access in reserve_sfa_size() Paolo Valerio
@ 2022-04-15 10:25 ` Eelco Chaudron
2022-04-15 11:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Eelco Chaudron @ 2022-04-15 10:25 UTC (permalink / raw)
To: Paolo Valerio
Cc: netdev, dev, Jakub Kicinski, Paolo Abeni, David S. Miller, stable
On 15 Apr 2022, at 10:08, Paolo Valerio wrote:
> Given a sufficiently large number of actions, while copying and
> reserving memory for a new action of a new flow, if next_offset is
> greater than MAX_ACTIONS_BUFSIZE, the function reserve_sfa_size() does
> not return -EMSGSIZE as expected, but it allocates MAX_ACTIONS_BUFSIZE
> bytes increasing actions_len by req_size. This can then lead to an OOB
> write access, especially when further actions need to be copied.
>
> Fix it by rearranging the flow action size check.
>
> KASAN splat below:
>
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in reserve_sfa_size+0x1ba/0x380 [openvswitch]
> Write of size 65360 at addr ffff888147e4001c by task handler15/836
>
> CPU: 1 PID: 836 Comm: handler15 Not tainted 5.18.0-rc1+ #27
> ...
> Call Trace:
> <TASK>
> dump_stack_lvl+0x45/0x5a
> print_report.cold+0x5e/0x5db
> ? __lock_text_start+0x8/0x8
> ? reserve_sfa_size+0x1ba/0x380 [openvswitch]
> kasan_report+0xb5/0x130
> ? reserve_sfa_size+0x1ba/0x380 [openvswitch]
> kasan_check_range+0xf5/0x1d0
> memcpy+0x39/0x60
> reserve_sfa_size+0x1ba/0x380 [openvswitch]
> __add_action+0x24/0x120 [openvswitch]
> ovs_nla_add_action+0xe/0x20 [openvswitch]
> ovs_ct_copy_action+0x29d/0x1130 [openvswitch]
> ? __kernel_text_address+0xe/0x30
> ? unwind_get_return_address+0x56/0xa0
> ? create_prof_cpu_mask+0x20/0x20
> ? ovs_ct_verify+0xf0/0xf0 [openvswitch]
> ? prep_compound_page+0x198/0x2a0
> ? __kasan_check_byte+0x10/0x40
> ? kasan_unpoison+0x40/0x70
> ? ksize+0x44/0x60
> ? reserve_sfa_size+0x75/0x380 [openvswitch]
> __ovs_nla_copy_actions+0xc26/0x2070 [openvswitch]
> ? __zone_watermark_ok+0x420/0x420
> ? validate_set.constprop.0+0xc90/0xc90 [openvswitch]
> ? __alloc_pages+0x1a9/0x3e0
> ? __alloc_pages_slowpath.constprop.0+0x1da0/0x1da0
> ? unwind_next_frame+0x991/0x1e40
> ? __mod_node_page_state+0x99/0x120
> ? __mod_lruvec_page_state+0x2e3/0x470
> ? __kasan_kmalloc_large+0x90/0xe0
> ovs_nla_copy_actions+0x1b4/0x2c0 [openvswitch]
> ovs_flow_cmd_new+0x3cd/0xb10 [openvswitch]
> ...
>
> Cc: stable@vger.kernel.org
> Fixes: f28cd2af22a0 ("openvswitch: fix flow actions reallocation")
> Signed-off-by: Paolo Valerio <pvalerio@redhat.com>
Change looks fine to me.
Acked-by: Eelco Chaudron <echaudro@redhat.com>
> ---
> net/openvswitch/flow_netlink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
> index 7176156d3844..4c09cf8a0ab2 100644
> --- a/net/openvswitch/flow_netlink.c
> +++ b/net/openvswitch/flow_netlink.c
> @@ -2465,7 +2465,7 @@ static struct nlattr *reserve_sfa_size(struct sw_flow_actions **sfa,
> 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) {
> + if ((next_offset + req_size) > MAX_ACTIONS_BUFSIZE) {
> OVS_NLERR(log, "Flow action size exceeds max %u",
> MAX_ACTIONS_BUFSIZE);
> return ERR_PTR(-EMSGSIZE);
>
> _______________________________________________
> dev mailing list
> dev@openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] openvswitch: fix OOB access in reserve_sfa_size()
2022-04-15 8:08 [PATCH] openvswitch: fix OOB access in reserve_sfa_size() Paolo Valerio
2022-04-15 10:25 ` [ovs-dev] " Eelco Chaudron
@ 2022-04-15 11:00 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-04-15 11:00 UTC (permalink / raw)
To: Paolo Valerio; +Cc: netdev, dev, pshelar, davem, kuba, pabeni, stable
Hello:
This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:
On Fri, 15 Apr 2022 10:08:41 +0200 you wrote:
> Given a sufficiently large number of actions, while copying and
> reserving memory for a new action of a new flow, if next_offset is
> greater than MAX_ACTIONS_BUFSIZE, the function reserve_sfa_size() does
> not return -EMSGSIZE as expected, but it allocates MAX_ACTIONS_BUFSIZE
> bytes increasing actions_len by req_size. This can then lead to an OOB
> write access, especially when further actions need to be copied.
>
> [...]
Here is the summary with links:
- openvswitch: fix OOB access in reserve_sfa_size()
https://git.kernel.org/netdev/net/c/cefa91b2332d
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
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2022-04-15 8:08 [PATCH] openvswitch: fix OOB access in reserve_sfa_size() Paolo Valerio
2022-04-15 10:25 ` [ovs-dev] " Eelco Chaudron
2022-04-15 11:00 ` patchwork-bot+netdevbpf
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