* Wrong date/time of messages (was: [Intel-wired-lan] [PATCH intel-next 0/2] ice: ethtool -L fixes)
2021-10-26 16:47 [PATCH intel-next 0/2] ice: ethtool -L fixes Maciej Fijalkowski
@ 2021-10-26 15:30 ` Paul Menzel
2021-10-26 16:47 ` [PATCH intel-next 1/2] ice: fix vsi->txq_map sizing Maciej Fijalkowski
2021-10-26 16:47 ` [PATCH intel-next 2/2] ice: avoid bpf_prog refcount underflow Maciej Fijalkowski
2 siblings, 0 replies; 6+ messages in thread
From: Paul Menzel @ 2021-10-26 15:30 UTC (permalink / raw)
To: Maciej Fijalkowski
Cc: alexandr.lobakin, netdev, marta.a.plantykow, kuba, bpf, davem,
magnus.karlsson, intel-wired-lan
Dear Intel folks,
On 26.10.21 18:47, Maciej Fijalkowski wrote:
[…]
Once again messages were sent to the list with a Date from the future.
Why can’t Intel employees work on systems with a correct clock?
It’d would be great if somebody from Intel would at least have the
courtesy to analyze and fix the root cause.
Kind regards,
Paul
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH intel-next 1/2] ice: fix vsi->txq_map sizing
2021-10-26 16:47 [PATCH intel-next 0/2] ice: ethtool -L fixes Maciej Fijalkowski
2021-10-26 15:30 ` Wrong date/time of messages (was: [Intel-wired-lan] [PATCH intel-next 0/2] ice: ethtool -L fixes) Paul Menzel
@ 2021-10-26 16:47 ` Maciej Fijalkowski
2021-11-18 9:05 ` [Intel-wired-lan] " Bhandare, KiranX
2021-10-26 16:47 ` [PATCH intel-next 2/2] ice: avoid bpf_prog refcount underflow Maciej Fijalkowski
2 siblings, 1 reply; 6+ messages in thread
From: Maciej Fijalkowski @ 2021-10-26 16:47 UTC (permalink / raw)
To: intel-wired-lan
Cc: netdev, bpf, anthony.l.nguyen, kuba, davem, marta.a.plantykow,
alexandr.lobakin, magnus.karlsson, Maciej Fijalkowski
The approach of having XDP queue per CPU regardless of user's setting
exposed a hidden bug that could occur in case when Rx queue count differ
from Tx queue count. Currently vsi->txq_map's size is equal to the
doubled vsi->alloc_txq, which is not correct due to the fact that XDP
rings were previously based on the Rx queue count. Below splat can be
seen when ethtool -L is used and XDP rings are configured:
[ 682.875339] BUG: kernel NULL pointer dereference, address: 000000000000000f
[ 682.883403] #PF: supervisor read access in kernel mode
[ 682.889345] #PF: error_code(0x0000) - not-present page
[ 682.895289] PGD 0 P4D 0
[ 682.898218] Oops: 0000 [#1] PREEMPT SMP PTI
[ 682.903055] CPU: 42 PID: 2878 Comm: ethtool Tainted: G OE 5.15.0-rc5+ #1
[ 682.912214] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS GRRFCRB1.86B.0276.D07.1605190235 05/19/2016
[ 682.923380] RIP: 0010:devres_remove+0x44/0x130
[ 682.928527] Code: 49 89 f4 55 48 89 fd 4c 89 ff 53 48 83 ec 10 e8 92 b9 49 00 48 8b 9d a8 02 00 00 48 8d 8d a0 02 00 00 49 89 c2 48 39 cb 74 0f <4c> 3b 63 10 74 25 48 8b 5b 08 48 39 cb 75 f1 4c 89 ff 4c 89 d6 e8
[ 682.950237] RSP: 0018:ffffc90006a679f0 EFLAGS: 00010002
[ 682.956285] RAX: 0000000000000286 RBX: ffffffffffffffff RCX: ffff88908343a370
[ 682.964538] RDX: 0000000000000001 RSI: ffffffff81690d60 RDI: 0000000000000000
[ 682.972789] RBP: ffff88908343a0d0 R08: 0000000000000000 R09: 0000000000000000
[ 682.981040] R10: 0000000000000286 R11: 3fffffffffffffff R12: ffffffff81690d60
[ 682.989282] R13: ffffffff81690a00 R14: ffff8890819807a8 R15: ffff88908343a36c
[ 682.997535] FS: 00007f08c7bfa740(0000) GS:ffff88a03fd00000(0000) knlGS:0000000000000000
[ 683.006910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 683.013557] CR2: 000000000000000f CR3: 0000001080a66003 CR4: 00000000003706e0
[ 683.021819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 683.030075] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 683.038336] Call Trace:
[ 683.041167] devm_kfree+0x33/0x50
[ 683.045004] ice_vsi_free_arrays+0x5e/0xc0 [ice]
[ 683.050380] ice_vsi_rebuild+0x4c8/0x750 [ice]
[ 683.055543] ice_vsi_recfg_qs+0x9a/0x110 [ice]
[ 683.060697] ice_set_channels+0x14f/0x290 [ice]
[ 683.065962] ethnl_set_channels+0x333/0x3f0
[ 683.070807] genl_family_rcv_msg_doit+0xea/0x150
[ 683.076152] genl_rcv_msg+0xde/0x1d0
[ 683.080289] ? channels_prepare_data+0x60/0x60
[ 683.085432] ? genl_get_cmd+0xd0/0xd0
[ 683.089667] netlink_rcv_skb+0x50/0xf0
[ 683.094006] genl_rcv+0x24/0x40
[ 683.097638] netlink_unicast+0x239/0x340
[ 683.102177] netlink_sendmsg+0x22e/0x470
[ 683.106717] sock_sendmsg+0x5e/0x60
[ 683.110756] __sys_sendto+0xee/0x150
[ 683.114894] ? handle_mm_fault+0xd0/0x2a0
[ 683.119535] ? do_user_addr_fault+0x1f3/0x690
[ 683.134173] __x64_sys_sendto+0x25/0x30
[ 683.148231] do_syscall_64+0x3b/0xc0
[ 683.161992] entry_SYSCALL_64_after_hwframe+0x44/0xae
Fix this by taking into account the value that num_possible_cpus()
yields in addition to vsi->alloc_txq instead of doubling the latter.
Fixes: efc2214b6047 ("ice: Add support for XDP")
Fixes: 22bf877e528f ("ice: introduce XDP_TX fallback path")
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
---
drivers/net/ethernet/intel/ice/ice_lib.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
index 3adbd9a179a7..e179bd5a688b 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_lib.c
@@ -83,8 +83,13 @@ static int ice_vsi_alloc_arrays(struct ice_vsi *vsi)
if (!vsi->rx_rings)
goto err_rings;
- /* XDP will have vsi->alloc_txq Tx queues as well, so double the size */
- vsi->txq_map = devm_kcalloc(dev, (2 * vsi->alloc_txq),
+ /* txq_map needs to have enough space to track both Tx (stack) rings
+ * and XDP rings; at this point vsi->num_xdp_txq might not be set,
+ * so use num_possible_cpus() as we want to always provide XDP ring
+ * per CPU, regardless of queue count settings from user that might
+ * have come from ethtool's set_channels() callback;
+ */
+ vsi->txq_map = devm_kcalloc(dev, (vsi->alloc_txq + num_possible_cpus()),
sizeof(*vsi->txq_map), GFP_KERNEL);
if (!vsi->txq_map)
--
2.31.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* RE: [Intel-wired-lan] [PATCH intel-next 1/2] ice: fix vsi->txq_map sizing
2021-10-26 16:47 ` [PATCH intel-next 1/2] ice: fix vsi->txq_map sizing Maciej Fijalkowski
@ 2021-11-18 9:05 ` Bhandare, KiranX
0 siblings, 0 replies; 6+ messages in thread
From: Bhandare, KiranX @ 2021-11-18 9:05 UTC (permalink / raw)
To: Fijalkowski, Maciej, intel-wired-lan
Cc: Lobakin, Alexandr, netdev, Plantykow, Marta A, kuba, bpf, davem,
Karlsson, Magnus
> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
> Maciej Fijalkowski
> Sent: Tuesday, October 26, 2021 10:17 PM
> To: intel-wired-lan@lists.osuosl.org
> Cc: Lobakin, Alexandr <alexandr.lobakin@intel.com>;
> netdev@vger.kernel.org; Plantykow, Marta A
> <marta.a.plantykow@intel.com>; kuba@kernel.org; bpf@vger.kernel.org;
> davem@davemloft.net; Karlsson, Magnus <magnus.karlsson@intel.com>
> Subject: [Intel-wired-lan] [PATCH intel-next 1/2] ice: fix vsi->txq_map sizing
>
> The approach of having XDP queue per CPU regardless of user's setting
> exposed a hidden bug that could occur in case when Rx queue count differ
> from Tx queue count. Currently vsi->txq_map's size is equal to the doubled
> vsi->alloc_txq, which is not correct due to the fact that XDP rings were
> previously based on the Rx queue count. Below splat can be seen when
> ethtool -L is used and XDP rings are configured:
>
> [ 682.875339] BUG: kernel NULL pointer dereference, address:
> 000000000000000f [ 682.883403] #PF: supervisor read access in kernel mode
> [ 682.889345] #PF: error_code(0x0000) - not-present page [ 682.895289]
> PGD 0 P4D 0 [ 682.898218] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 682.903055] CPU: 42 PID: 2878 Comm: ethtool Tainted: G OE 5.15.0-
> rc5+ #1
> [ 682.912214] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS
> GRRFCRB1.86B.0276.D07.1605190235 05/19/2016 [ 682.923380] RIP:
> 0010:devres_remove+0x44/0x130 [ 682.928527] Code: 49 89 f4 55 48 89 fd
> 4c 89 ff 53 48 83 ec 10 e8 92 b9 49 00 48 8b 9d a8 02 00 00 48 8d 8d a0 02 00
> 00 49 89 c2 48 39 cb 74 0f <4c> 3b 63 10 74 25 48 8b 5b 08 48 39 cb 75 f1 4c
> 89 ff 4c 89 d6 e8 [ 682.950237] RSP: 0018:ffffc90006a679f0 EFLAGS:
> 00010002 [ 682.956285] RAX: 0000000000000286 RBX: ffffffffffffffff RCX:
> ffff88908343a370 [ 682.964538] RDX: 0000000000000001 RSI:
> ffffffff81690d60 RDI: 0000000000000000 [ 682.972789] RBP:
> ffff88908343a0d0 R08: 0000000000000000 R09: 0000000000000000 [
> 682.981040] R10: 0000000000000286 R11: 3fffffffffffffff R12: ffffffff81690d60
> [ 682.989282] R13: ffffffff81690a00 R14: ffff8890819807a8 R15:
> ffff88908343a36c [ 682.997535] FS: 00007f08c7bfa740(0000)
> GS:ffff88a03fd00000(0000) knlGS:0000000000000000 [ 683.006910] CS: 0010
> DS: 0000 ES: 0000 CR0: 0000000080050033 [ 683.013557] CR2:
> 000000000000000f CR3: 0000001080a66003 CR4: 00000000003706e0 [
> 683.021819] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000 [ 683.030075] DR3: 0000000000000000 DR6:
> 00000000fffe0ff0 DR7: 0000000000000400 [ 683.038336] Call Trace:
> [ 683.041167] devm_kfree+0x33/0x50
> [ 683.045004] ice_vsi_free_arrays+0x5e/0xc0 [ice] [ 683.050380]
> ice_vsi_rebuild+0x4c8/0x750 [ice] [ 683.055543]
> ice_vsi_recfg_qs+0x9a/0x110 [ice] [ 683.060697]
> ice_set_channels+0x14f/0x290 [ice] [ 683.065962]
> ethnl_set_channels+0x333/0x3f0 [ 683.070807]
> genl_family_rcv_msg_doit+0xea/0x150
> [ 683.076152] genl_rcv_msg+0xde/0x1d0
> [ 683.080289] ? channels_prepare_data+0x60/0x60 [ 683.085432] ?
> genl_get_cmd+0xd0/0xd0 [ 683.089667] netlink_rcv_skb+0x50/0xf0 [
> 683.094006] genl_rcv+0x24/0x40 [ 683.097638]
> netlink_unicast+0x239/0x340 [ 683.102177] netlink_sendmsg+0x22e/0x470 [
> 683.106717] sock_sendmsg+0x5e/0x60 [ 683.110756]
> __sys_sendto+0xee/0x150 [ 683.114894] ? handle_mm_fault+0xd0/0x2a0 [
> 683.119535] ? do_user_addr_fault+0x1f3/0x690 [ 683.134173]
> __x64_sys_sendto+0x25/0x30 [ 683.148231] do_syscall_64+0x3b/0xc0 [
> 683.161992] entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Fix this by taking into account the value that num_possible_cpus() yields in
> addition to vsi->alloc_txq instead of doubling the latter.
>
> Fixes: efc2214b6047 ("ice: Add support for XDP")
> Fixes: 22bf877e528f ("ice: introduce XDP_TX fallback path")
> Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> ---
> drivers/net/ethernet/intel/ice/ice_lib.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
Tested-by: Kiran Bhandare <kiranx.bhandare@intel.com> A Contingent Worker at Intel
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH intel-next 2/2] ice: avoid bpf_prog refcount underflow
2021-10-26 16:47 [PATCH intel-next 0/2] ice: ethtool -L fixes Maciej Fijalkowski
2021-10-26 15:30 ` Wrong date/time of messages (was: [Intel-wired-lan] [PATCH intel-next 0/2] ice: ethtool -L fixes) Paul Menzel
2021-10-26 16:47 ` [PATCH intel-next 1/2] ice: fix vsi->txq_map sizing Maciej Fijalkowski
@ 2021-10-26 16:47 ` Maciej Fijalkowski
2021-11-18 9:03 ` [Intel-wired-lan] " Bhandare, KiranX
2 siblings, 1 reply; 6+ messages in thread
From: Maciej Fijalkowski @ 2021-10-26 16:47 UTC (permalink / raw)
To: intel-wired-lan
Cc: netdev, bpf, anthony.l.nguyen, kuba, davem, marta.a.plantykow,
alexandr.lobakin, magnus.karlsson, Maciej Fijalkowski
From: Marta Plantykow <marta.a.plantykow@intel.com>
Ice driver has the routines for managing XDP resources that are shared
between ndo_bpf op and VSI rebuild flow. The latter takes place for
example when user changes queue count on an interface via ethtool's
set_channels().
There is an issue around the bpf_prog refcounting when VSI is being
rebuilt - since ice_prepare_xdp_rings() is called with vsi->xdp_prog as
an argument that is used later on by ice_vsi_assign_bpf_prog(), same
bpf_prog pointers are swapped with each other. Then it is also
interpreted as an 'old_prog' which in turn causes us to call
bpf_prog_put on it that will decrement its refcount.
Below splat can be interpreted in a way that due to zero refcount of a
bpf_prog it is wiped out from the system while kernel still tries to
refer to it:
[ 481.069429] BUG: unable to handle page fault for address: ffffc9000640f038
[ 481.077390] #PF: supervisor read access in kernel mode
[ 481.083335] #PF: error_code(0x0000) - not-present page
[ 481.089276] PGD 100000067 P4D 100000067 PUD 1001cb067 PMD 106d2b067 PTE 0
[ 481.097141] Oops: 0000 [#1] PREEMPT SMP PTI
[ 481.101980] CPU: 12 PID: 3339 Comm: sudo Tainted: G OE 5.15.0-rc5+ #1
[ 481.110840] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS GRRFCRB1.86B.0276.D07.1605190235 05/19/2016
[ 481.122021] RIP: 0010:dev_xdp_prog_id+0x25/0x40
[ 481.127265] Code: 80 00 00 00 00 0f 1f 44 00 00 89 f6 48 c1 e6 04 48 01 fe 48 8b 86 98 08 00 00 48 85 c0 74 13 48 8b 50 18 31 c0 48 85 d2 74 07 <48> 8b 42 38 8b 40 20 c3 48 8b 96 90 08 00 00 eb e8 66 2e 0f 1f 84
[ 481.148991] RSP: 0018:ffffc90007b63868 EFLAGS: 00010286
[ 481.155034] RAX: 0000000000000000 RBX: ffff889080824000 RCX: 0000000000000000
[ 481.163278] RDX: ffffc9000640f000 RSI: ffff889080824010 RDI: ffff889080824000
[ 481.171527] RBP: ffff888107af7d00 R08: 0000000000000000 R09: ffff88810db5f6e0
[ 481.179776] R10: 0000000000000000 R11: ffff8890885b9988 R12: ffff88810db5f4bc
[ 481.188026] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 481.196276] FS: 00007f5466d5bec0(0000) GS:ffff88903fb00000(0000) knlGS:0000000000000000
[ 481.205633] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 481.212279] CR2: ffffc9000640f038 CR3: 000000014429c006 CR4: 00000000003706e0
[ 481.220530] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 481.228771] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 481.237029] Call Trace:
[ 481.239856] rtnl_fill_ifinfo+0x768/0x12e0
[ 481.244602] rtnl_dump_ifinfo+0x525/0x650
[ 481.249246] ? __alloc_skb+0xa5/0x280
[ 481.253484] netlink_dump+0x168/0x3c0
[ 481.257725] netlink_recvmsg+0x21e/0x3e0
[ 481.262263] ____sys_recvmsg+0x87/0x170
[ 481.266707] ? __might_fault+0x20/0x30
[ 481.271046] ? _copy_from_user+0x66/0xa0
[ 481.275591] ? iovec_from_user+0xf6/0x1c0
[ 481.280226] ___sys_recvmsg+0x82/0x100
[ 481.284566] ? sock_sendmsg+0x5e/0x60
[ 481.288791] ? __sys_sendto+0xee/0x150
[ 481.293129] __sys_recvmsg+0x56/0xa0
[ 481.297267] do_syscall_64+0x3b/0xc0
[ 481.301395] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 481.307238] RIP: 0033:0x7f5466f39617
[ 481.311373] Code: 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb bd 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2f 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
[ 481.342944] RSP: 002b:00007ffedc7f4308 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
[ 481.361783] RAX: ffffffffffffffda RBX: 00007ffedc7f5460 RCX: 00007f5466f39617
[ 481.380278] RDX: 0000000000000000 RSI: 00007ffedc7f5360 RDI: 0000000000000003
[ 481.398500] RBP: 00007ffedc7f53f0 R08: 0000000000000000 R09: 000055d556f04d50
[ 481.416463] R10: 0000000000000077 R11: 0000000000000246 R12: 00007ffedc7f5360
[ 481.434131] R13: 00007ffedc7f5350 R14: 00007ffedc7f5344 R15: 0000000000000e98
[ 481.451520] Modules linked in: ice(OE) af_packet binfmt_misc nls_iso8859_1 ipmi_ssif intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp mxm_wmi mei_me coretemp mei ipmi_si ipmi_msghandler wmi acpi_pad acpi_power_meter ip_tables x_tables autofs4 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel ahci crypto_simd cryptd libahci lpc_ich [last unloaded: ice]
[ 481.528558] CR2: ffffc9000640f038
[ 481.542041] ---[ end trace d1f24c9ecf5b61c1 ]---
Fix this by only calling ice_vsi_assign_bpf_prog() inside
ice_prepare_xdp_rings() when current vsi->xdp_prog pointer is NULL.
This way set_channels() flow will not attempt to swap the vsi->xdp_prog
pointers with itself.
Also, sprinkle around some comments that provide a reasoning about
correlation between driver and kernel in terms of bpf_prog refcount.
Fixes: efc2214b6047 ("ice: Add support for XDP")
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Marta Plantykow <marta.a.plantykow@intel.com>
[ Maciej: don't assign the prog if already present, expand commit
message ]
Co-developed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
---
drivers/net/ethernet/intel/ice/ice_main.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index cabe84bb29fe..aff6e388fdd9 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -2501,7 +2501,18 @@ int ice_prepare_xdp_rings(struct ice_vsi *vsi, struct bpf_prog *prog)
ice_stat_str(status));
goto clear_xdp_rings;
}
- ice_vsi_assign_bpf_prog(vsi, prog);
+
+ /* assign the prog only when it's not already present on VSI;
+ * this flow is a subject of both ethtool -L and ndo_bpf flows;
+ * VSI rebuild that happens under ethtool -L can expose us to
+ * the bpf_prog refcount issues as we would be swapping same
+ * bpf_prog pointers from vsi->xdp_prog and calling bpf_prog_put
+ * on it as it would be treated as an 'old_prog'; for ndo_bpf
+ * this is not harmful as dev_xdp_install bumps the refcount
+ * before calling the op exposed by the driver;
+ */
+ if (!ice_is_xdp_ena_vsi(vsi))
+ ice_vsi_assign_bpf_prog(vsi, prog);
return 0;
clear_xdp_rings:
@@ -2647,6 +2658,11 @@ ice_xdp_setup_prog(struct ice_vsi *vsi, struct bpf_prog *prog,
if (xdp_ring_err)
NL_SET_ERR_MSG_MOD(extack, "Freeing XDP Tx resources failed");
} else {
+ /* safe to call even when prog == vsi->xdp_prog as
+ * dev_xdp_install in net/core/dev.c incremented prog's
+ * refcount so corresponding bpf_prog_put won't cause
+ * underflow
+ */
ice_vsi_assign_bpf_prog(vsi, prog);
}
--
2.31.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* RE: [Intel-wired-lan] [PATCH intel-next 2/2] ice: avoid bpf_prog refcount underflow
2021-10-26 16:47 ` [PATCH intel-next 2/2] ice: avoid bpf_prog refcount underflow Maciej Fijalkowski
@ 2021-11-18 9:03 ` Bhandare, KiranX
0 siblings, 0 replies; 6+ messages in thread
From: Bhandare, KiranX @ 2021-11-18 9:03 UTC (permalink / raw)
To: Fijalkowski, Maciej, intel-wired-lan
Cc: Lobakin, Alexandr, netdev, Plantykow, Marta A, kuba, bpf, davem,
Karlsson, Magnus
> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of
> Maciej Fijalkowski
> Sent: Tuesday, October 26, 2021 10:17 PM
> To: intel-wired-lan@lists.osuosl.org
> Cc: Lobakin, Alexandr <alexandr.lobakin@intel.com>;
> netdev@vger.kernel.org; Plantykow, Marta A
> <marta.a.plantykow@intel.com>; kuba@kernel.org; bpf@vger.kernel.org;
> davem@davemloft.net; Karlsson, Magnus <magnus.karlsson@intel.com>
> Subject: [Intel-wired-lan] [PATCH intel-next 2/2] ice: avoid bpf_prog refcount
> underflow
>
> From: Marta Plantykow <marta.a.plantykow@intel.com>
>
> Ice driver has the routines for managing XDP resources that are shared
> between ndo_bpf op and VSI rebuild flow. The latter takes place for example
> when user changes queue count on an interface via ethtool's set_channels().
>
> There is an issue around the bpf_prog refcounting when VSI is being rebuilt -
> since ice_prepare_xdp_rings() is called with vsi->xdp_prog as an argument
> that is used later on by ice_vsi_assign_bpf_prog(), same bpf_prog pointers
> are swapped with each other. Then it is also interpreted as an 'old_prog'
> which in turn causes us to call bpf_prog_put on it that will decrement its
> refcount.
>
> Below splat can be interpreted in a way that due to zero refcount of a
> bpf_prog it is wiped out from the system while kernel still tries to refer to it:
>
> [ 481.069429] BUG: unable to handle page fault for address:
> ffffc9000640f038 [ 481.077390] #PF: supervisor read access in kernel mode [
> 481.083335] #PF: error_code(0x0000) - not-present page [ 481.089276] PGD
> 100000067 P4D 100000067 PUD 1001cb067 PMD 106d2b067 PTE 0 [
> 481.097141] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 481.101980] CPU: 12 PID: 3339 Comm: sudo Tainted: G OE 5.15.0-
> rc5+ #1
> [ 481.110840] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS
> GRRFCRB1.86B.0276.D07.1605190235 05/19/2016 [ 481.122021] RIP:
> 0010:dev_xdp_prog_id+0x25/0x40 [ 481.127265] Code: 80 00 00 00 00 0f 1f
> 44 00 00 89 f6 48 c1 e6 04 48 01 fe 48 8b 86 98 08 00 00 48 85 c0 74 13 48 8b
> 50 18 31 c0 48 85 d2 74 07 <48> 8b 42 38 8b 40 20 c3 48 8b 96 90 08 00 00 eb
> e8 66 2e 0f 1f 84 [ 481.148991] RSP: 0018:ffffc90007b63868 EFLAGS:
> 00010286 [ 481.155034] RAX: 0000000000000000 RBX: ffff889080824000
> RCX: 0000000000000000 [ 481.163278] RDX: ffffc9000640f000 RSI:
> ffff889080824010 RDI: ffff889080824000 [ 481.171527] RBP:
> ffff888107af7d00 R08: 0000000000000000 R09: ffff88810db5f6e0 [
> 481.179776] R10: 0000000000000000 R11: ffff8890885b9988 R12:
> ffff88810db5f4bc [ 481.188026] R13: 0000000000000000 R14:
> 0000000000000000 R15: 0000000000000000 [ 481.196276] FS:
> 00007f5466d5bec0(0000) GS:ffff88903fb00000(0000)
> knlGS:0000000000000000 [ 481.205633] CS: 0010 DS: 0000 ES: 0000 CR0:
> 0000000080050033 [ 481.212279] CR2: ffffc9000640f038 CR3:
> 000000014429c006 CR4: 00000000003706e0 [ 481.220530] DR0:
> 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [
> 481.228771] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
> 0000000000000400 [ 481.237029] Call Trace:
> [ 481.239856] rtnl_fill_ifinfo+0x768/0x12e0 [ 481.244602]
> rtnl_dump_ifinfo+0x525/0x650 [ 481.249246] ? __alloc_skb+0xa5/0x280 [
> 481.253484] netlink_dump+0x168/0x3c0 [ 481.257725]
> netlink_recvmsg+0x21e/0x3e0 [ 481.262263] ____sys_recvmsg+0x87/0x170
> [ 481.266707] ? __might_fault+0x20/0x30 [ 481.271046] ?
> _copy_from_user+0x66/0xa0 [ 481.275591] ? iovec_from_user+0xf6/0x1c0 [
> 481.280226] ___sys_recvmsg+0x82/0x100 [ 481.284566] ?
> sock_sendmsg+0x5e/0x60 [ 481.288791] ? __sys_sendto+0xee/0x150 [
> 481.293129] __sys_recvmsg+0x56/0xa0 [ 481.297267]
> do_syscall_64+0x3b/0xc0 [ 481.301395]
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> [ 481.307238] RIP: 0033:0x7f5466f39617
> [ 481.311373] Code: 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb bd 0f 1f 00 f3 0f
> 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2f 00 00 00 0f 05 <48> 3d 00 f0 ff
> ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10 [ 481.342944] RSP:
> 002b:00007ffedc7f4308 EFLAGS: 00000246 ORIG_RAX: 000000000000002f [
> 481.361783] RAX: ffffffffffffffda RBX: 00007ffedc7f5460 RCX:
> 00007f5466f39617 [ 481.380278] RDX: 0000000000000000 RSI:
> 00007ffedc7f5360 RDI: 0000000000000003 [ 481.398500] RBP:
> 00007ffedc7f53f0 R08: 0000000000000000 R09: 000055d556f04d50 [
> 481.416463] R10: 0000000000000077 R11: 0000000000000246 R12:
> 00007ffedc7f5360 [ 481.434131] R13: 00007ffedc7f5350 R14:
> 00007ffedc7f5344 R15: 0000000000000e98 [ 481.451520] Modules linked in:
> ice(OE) af_packet binfmt_misc nls_iso8859_1 ipmi_ssif intel_rapl_msr
> intel_rapl_common x86_pkg_temp_thermal intel_powerclamp mxm_wmi
> mei_me coretemp mei ipmi_si ipmi_msghandler wmi acpi_pad
> acpi_power_meter ip_tables x_tables autofs4 crct10dif_pclmul crc32_pclmul
> ghash_clmulni_intel aesni_intel ahci crypto_simd cryptd libahci lpc_ich [last
> unloaded: ice] [ 481.528558] CR2: ffffc9000640f038 [ 481.542041] ---[ end
> trace d1f24c9ecf5b61c1 ]---
>
> Fix this by only calling ice_vsi_assign_bpf_prog() inside
> ice_prepare_xdp_rings() when current vsi->xdp_prog pointer is NULL.
> This way set_channels() flow will not attempt to swap the vsi->xdp_prog
> pointers with itself.
>
> Also, sprinkle around some comments that provide a reasoning about
> correlation between driver and kernel in terms of bpf_prog refcount.
>
> Fixes: efc2214b6047 ("ice: Add support for XDP")
> Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> Signed-off-by: Marta Plantykow <marta.a.plantykow@intel.com> [ Maciej:
> don't assign the prog if already present, expand commit
> message ]
> Co-developed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> ---
> drivers/net/ethernet/intel/ice/ice_main.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
Tested-by: Kiran Bhandare <kiranx.bhandare@intel.com> A Contingent Worker at Intel
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