4.4.298-rc1 review

This is the start of the stable review cycle for the 4.4.298 release. There are 11 patches in this series, all will be posted as a response to this one. If anyone has any issues with these being applied, please let me know.

Responses should be made by Wed, 05 Jan 2022 14:20:40 +0000. Anything received after that time might be too late.

The whole patch series can be found in one patch at:

	https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.4.298-rc1.gz

or in the git tree and branch at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.4.y
and the diffstat can be found below.

thanks,

greg k-h

-------------
Pseudo-Shortlog of commits:

Greg Kroah-Hartman <[email protected]>

    Linux 4.4.298-rc1

Muchun Song <[email protected]>
net: fix use-after-free in tw_timer_handler

Leo L. Schwab <[email protected]>
Input: spaceball - fix parsing of movement data packets

Pavel Skripkin <[email protected]>
Input: appletouch - initialize work before device registration

Alexey Makhalov <[email protected]>
scsi: vmw_pvscsi: Set residual data length conditionally

Vincent Pelletier <[email protected]>
usb: gadget: f_fs: Clear ffs_eventfd in ffs_data_clear.

Mathias Nyman <[email protected]>
xhci: Fresco FL1100 controller should not have BROKEN_MSI quirk set.

Dmitry V. Levin <[email protected]>
uapi: fix linux/nfc.h userspace compilation errors

Krzysztof Kozlowski <[email protected]>
nfc: uapi: use kernel size_t to fix user-space builds

Tom Rix <[email protected]>
selinux: initialize proto variable in selinux_ip_postroute_compat()

Heiko Carstens <[email protected]>
recordmcount.pl: fix typo in s390 mcount regex

Wang Qing <[email protected]>
platform/x86: apple-gmux: use resource_size() with res

-------------

Diffstat:

 Makefile                           |  4 ++--
 drivers/input/joystick/spaceball.c | 11 +++++++++--
 drivers/input/mouse/appletouch.c   |  4 ++--
 drivers/platform/x86/apple-gmux.c  |  2 +-
 drivers/scsi/vmw_pvscsi.c          |  7 +++++--
 drivers/usb/gadget/function/f_fs.c |  9 ++++++---
 drivers/usb/host/xhci-pci.c        |  5 ++++-
 include/uapi/linux/nfc.h           |  6 +++---
 net/ipv4/af_inet.c                 | 10 ++++------
 scripts/recordmcount.pl            |  2 +-
 security/selinux/hooks.c           |  2 +-
 11 files changed, 38 insertions(+), 24 deletions(-)

From: Wang Qing <[email protected]>

[ Upstream commit eb66fb03a727cde0ab9b1a3858de55c26f3007da ]

This should be (res->end - res->start + 1) here actually, use resource_size() derectly.

---
 drivers/platform/x86/apple-gmux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 976efeb3f2ba3..a0f10ccdca3e4 100644
@@ -461,7 +461,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
 	}
 
 	gmux_data->iostart = res->start;
-	gmux_data->iolen = res->end - res->start;
+	gmux_data->iolen = resource_size(res);
 
 	if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
 		pr_err("gmux I/O region too small (%lu < %u)\n",

2.34.1

From: Heiko Carstens <[email protected]>

commit 4eb1782eaa9fa1c224ad1fa0d13a9f09c3ab2d80 upstream.

Commit 85bf17b28f97 ("recordmcount.pl: look for jgnop instruction as well as bcrl on s390") added a new alternative mnemonic for the existing brcl instruction. This is required for the combination old gcc version (pre 9.0) and binutils since version 2.37.
However at the same time this commit introduced a typo, replacing brcl with bcrl. As a result no mcount locations are detected anymore with old gcc versions (pre 9.0) and binutils before version 2.37.
Fix this by using the correct mnemonic again.

---
 scripts/recordmcount.pl |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -248,7 +248,7 @@ if ($arch eq "x86_64") {
 
 } elsif ($arch eq "s390" && $bits == 64) {
     if ($cc =~ /-DCC_USING_HOTPATCH/) {
-	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*(bcrl\\s*0,|jgnop\\s*)[0-9a-f]+ <([^\+]*)>\$";
+	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*(brcl\\s*0,|jgnop\\s*)[0-9a-f]+ <([^\+]*)>\$";
 	$mcount_adjust = 0;
     } else {
 	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$";

From: Tom Rix <[email protected]>

commit 732bc2ff080c447f8524f40c970c481f5da6eed3 upstream.

Clang static analysis reports this warning

hooks.c:5765:6: warning: 4th function call argument is an uninitialized

                value
        if (selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto))
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

selinux_parse_skb() can return ok without setting proto. The later call to selinux_xfrm_postroute_last() does an early check of proto and can return ok if the garbage proto value matches. So initialize proto.

---
 security/selinux/hooks.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -4974,7 +4974,7 @@ static unsigned int selinux_ip_postroute
 	struct common_audit_data ad;
 	struct lsm_network_audit net = {0,};
 	char *addrp;
-	u8 proto;
+	u8 proto = 0;
 
 	if (sk == NULL)
 		return NF_ACCEPT;

From: Krzysztof Kozlowski <[email protected]>

commit 79b69a83705e621b258ac6d8ae6d3bfdb4b930aa upstream.

Fix user-space builds if it includes /usr/include/linux/nfc.h before some of other headers:

/usr/include/linux/nfc.h:281:9: error: unknown type name ‘size_t’

    281 |         size_t service_name_len;
        |         ^~~~~~

---
 include/uapi/linux/nfc.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -276,7 +276,7 @@ struct sockaddr_nfc_llcp {
 	__u8 dsap; /* Destination SAP, if known */
 	__u8 ssap; /* Source SAP to be bound to */
 	char service_name[NFC_LLCP_MAX_SERVICE_NAME]; /* Service name URI */;
-	size_t service_name_len;
+	__kernel_size_t service_name_len;
 };
 
 /* NFC socket protocols */

From: Dmitry V. Levin <[email protected]>

commit 7175f02c4e5f5a9430113ab9ca0fd0ce98b28a51 upstream.

Replace sa_family_t with __kernel_sa_family_t to fix the following linux/nfc.h userspace compilation errors:

/usr/include/linux/nfc.h:266:2: error: unknown type name 'sa_family_t'
sa_family_t sa_family;
/usr/include/linux/nfc.h:274:2: error: unknown type name 'sa_family_t'
sa_family_t sa_family;

---
 include/uapi/linux/nfc.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -261,7 +261,7 @@ enum nfc_sdp_attr {
 #define NFC_SE_ENABLED  0x1
 
 struct sockaddr_nfc {
-	sa_family_t sa_family;
+	__kernel_sa_family_t sa_family;
 	__u32 dev_idx;
 	__u32 target_idx;
 	__u32 nfc_protocol;

@@ -269,7 +269,7 @@ struct sockaddr_nfc {
 
 #define NFC_LLCP_MAX_SERVICE_NAME 63
 struct sockaddr_nfc_llcp {
-	sa_family_t sa_family;
+	__kernel_sa_family_t sa_family;
 	__u32 dev_idx;
 	__u32 target_idx;
 	__u32 nfc_protocol;

From: Mathias Nyman <[email protected]>

commit e4844092581ceec22489b66c42edc88bc6079783 upstream.

The Fresco Logic FL1100 controller needs the TRUST_TX_LENGTH quirk like other Fresco controllers, but should not have the BROKEN_MSI quirks set.

BROKEN_MSI quirk causes issues in detecting usb drives connected to docks with this FL1100 controller.
The BROKEN_MSI flag was apparently accidentally set together with the TRUST_TX_LENGTH quirk

Original patch went to stable so this should go there as well.

---
 drivers/usb/host/xhci-pci.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -91,7 +91,6 @@ static void xhci_pci_quirks(struct devic
 	/* Look for vendor-specific quirks */
 	if (pdev->vendor == PCI_VENDOR_ID_FRESCO_LOGIC &&
 			(pdev->device == PCI_DEVICE_ID_FRESCO_LOGIC_PDK ||
-			 pdev->device == PCI_DEVICE_ID_FRESCO_LOGIC_FL1100 ||
 			 pdev->device == PCI_DEVICE_ID_FRESCO_LOGIC_FL1400)) {
 		if (pdev->device == PCI_DEVICE_ID_FRESCO_LOGIC_PDK &&
 				pdev->revision == 0x0) {

@@ -126,6 +125,10 @@ static void xhci_pci_quirks(struct devic
 			pdev->device == PCI_DEVICE_ID_FRESCO_LOGIC_FL1009)
 		xhci->quirks |= XHCI_BROKEN_STREAMS;
 
+	if (pdev->vendor == PCI_VENDOR_ID_FRESCO_LOGIC &&
+			pdev->device == PCI_DEVICE_ID_FRESCO_LOGIC_FL1100)
+		xhci->quirks |= XHCI_TRUST_TX_LENGTH;
+
 	if (pdev->vendor == PCI_VENDOR_ID_NEC)
 		xhci->quirks |= XHCI_NEC_HOST;
 

From: Vincent Pelletier <[email protected]>

commit b1e0887379422975f237d43d8839b751a6bcf154 upstream.

ffs_data_clear is indirectly called from both ffs_fs_kill_sb and ffs_ep0_release, so it ends up being called twice when userland closes ep0 and then unmounts f_fs.
If userland provided an eventfd along with function's USB descriptors, it ends up calling eventfd_ctx_put as many times, causing a refcount underflow.
NULL-ify ffs_eventfd to prevent these extraneous eventfd_ctx_put calls.

Also, set epfiles to NULL right after de-allocating it, for readability.

For completeness, ffs_data_clear actually ends up being called thrice, the last call being before the whole ffs structure gets freed, so when this specific sequence happens there is a second underflow happening (but not being reported):

/sys/kernel/debug/tracing# modprobe usb_f_fs /sys/kernel/debug/tracing# echo ffs_data_clear > set_ftrace_filter /sys/kernel/debug/tracing# echo function > current_tracer /sys/kernel/debug/tracing# echo 1 > tracing_on
(setup gadget, run and kill function userland process, teardown gadget) /sys/kernel/debug/tracing# echo 0 > tracing_on /sys/kernel/debug/tracing# cat trace

 smartcard-openp-436     [000] .....  1946.208786: ffs_data_clear <-ffs_data_closed
 smartcard-openp-431     [000] .....  1946.279147: ffs_data_clear <-ffs_data_closed
 smartcard-openp-431     [000] .n...  1946.905512: ffs_data_clear <-ffs_data_put

Warning output corresponding to above trace:

[ 1946.284139] WARNING: CPU: 0 PID: 431 at lib/refcount.c:28 refcount_warn_saturate+0x110/0x15c
[ 1946.293094] refcount_t: underflow; use-after-free.
[ 1946.298164] Modules linked in: usb_f_ncm(E) u_ether(E) usb_f_fs(E) hci_uart(E) btqca(E) btrtl(E) btbcm(E) btintel(E) bluetooth(E) nls_ascii(E) nls_cp437(E) vfat(E) fat(E) bcm2835_v4l2(CE) bcm2835_mmal_vchiq(CE) videobuf2_vmalloc(E) videobuf2_memops(E) sha512_generic(E) videobuf2_v4l2(E) sha512_arm(E) videobuf2_common(E) videodev(E) cpufreq_dt(E) snd_bcm2835(CE) brcmfmac(E) mc(E) vc4(E) ctr(E) brcmutil(E) snd_soc_core(E) snd_pcm_dmaengine(E) drbg(E) snd_pcm(E) snd_timer(E) snd(E) soundcore(E) drm_kms_helper(E) cec(E) ansi_cprng(E) rc_core(E) syscopyarea(E) raspberrypi_cpufreq(E) sysfillrect(E) sysimgblt(E) cfg80211(E) max17040_battery(OE) raspberrypi_hwmon(E) fb_sys_fops(E) regmap_i2c(E) ecdh_generic(E) rfkill(E) ecc(E) bcm2835_rng(E) rng_core(E) vchiq(CE) leds_gpio(E) libcomposite(E) fuse(E) configfs(E) ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc16(E) mbcache(E) jbd2(E) crc32c_generic(E) sdhci_iproc(E) sdhci_pltfm(E) sdhci(E)
[ 1946.399633] CPU: 0 PID: 431 Comm: smartcard-openp Tainted: G         C OE     5.15.0-1-rpi #1  Debian 5.15.3-1
[ 1946.417950] Hardware name: BCM2835
[ 1946.425442] Backtrace:
[ 1946.432048] [<c08d60a0>] (dump_backtrace) from [<c08d62ec>] (show_stack+0x20/0x24)
[ 1946.448226]  r7:00000009 r6:0000001c r5:c04a948c r4:c0a64e2c
[ 1946.458412] [<c08d62cc>] (show_stack) from [<c08d9ae0>] (dump_stack+0x28/0x30)
[ 1946.470380] [<c08d9ab8>] (dump_stack) from [<c0123500>] (__warn+0xe8/0x154)
[ 1946.482067]  r5:c04a948c r4:c0a71dc8
[ 1946.490184] [<c0123418>] (__warn) from [<c08d6948>] (warn_slowpath_fmt+0xa0/0xe4)
[ 1946.506758]  r7:00000009 r6:0000001c r5:c0a71dc8 r4:c0a71e04
[ 1946.517070] [<c08d68ac>] (warn_slowpath_fmt) from [<c04a948c>] (refcount_warn_saturate+0x110/0x15c)
[ 1946.535309]  r8:c0100224 r7:c0dfcb84 r6:ffffffff r5:c3b84c00 r4:c24a17c0
[ 1946.546708] [<c04a937c>] (refcount_warn_saturate) from [<c0380134>] (eventfd_ctx_put+0x48/0x74)
[ 1946.564476] [<c03800ec>] (eventfd_ctx_put) from [<bf5464e8>] (ffs_data_clear+0xd0/0x118 [usb_f_fs])
[ 1946.582664]  r5:c3b84c00 r4:c2695b00
[ 1946.590668] [<bf546418>] (ffs_data_clear [usb_f_fs]) from [<bf547cc0>] (ffs_data_closed+0x9c/0x150 [usb_f_fs])
[ 1946.609608]  r5:bf54d014 r4:c2695b00
[ 1946.617522] [<bf547c24>] (ffs_data_closed [usb_f_fs]) from [<bf547da0>] (ffs_fs_kill_sb+0x2c/0x30 [usb_f_fs])
[ 1946.636217]  r7:c0dfcb84 r6:c3a12260 r5:bf54d014 r4:c229f000
[ 1946.646273] [<bf547d74>] (ffs_fs_kill_sb [usb_f_fs]) from [<c0326d50>] (deactivate_locked_super+0x54/0x9c)
[ 1946.664893]  r5:bf54d014 r4:c229f000
[ 1946.672921] [<c0326cfc>] (deactivate_locked_super) from [<c0326df8>] (deactivate_super+0x60/0x64)
[ 1946.690722]  r5:c2a09000 r4:c229f000
[ 1946.698706] [<c0326d98>] (deactivate_super) from [<c0349a28>] (cleanup_mnt+0xe4/0x14c)
[ 1946.715553]  r5:c2a09000 r4:00000000
[ 1946.723528] [<c0349944>] (cleanup_mnt) from [<c0349b08>] (__cleanup_mnt+0x1c/0x20)
[ 1946.739922]  r7:c0dfcb84 r6:c3a12260 r5:c3a126fc r4:00000000
[ 1946.750088] [<c0349aec>] (__cleanup_mnt) from [<c0143d10>] (task_work_run+0x84/0xb8)
[ 1946.766602] [<c0143c8c>] (task_work_run) from [<c010bdc8>] (do_work_pending+0x470/0x56c)
[ 1946.783540]  r7:5ac3c35a r6:c0d0424c r5:c200bfb0 r4:c200a000
[ 1946.793614] [<c010b958>] (do_work_pending) from [<c01000c0>] (slow_work_pending+0xc/0x20)
[ 1946.810553] Exception stack(0xc200bfb0 to 0xc200bff8)
[ 1946.820129] bfa0:                                     00000000 00000000 000000aa b5e21430
[ 1946.837104] bfc0: bef867a0 00000001 bef86840 00000034 bef86838 bef86790 bef86794 bef867a0
[ 1946.854125] bfe0: 00000000 bef86798 b67b7a1c b6d626a4 60000010 b5a23760
[ 1946.865335]  r10:00000000 r9:c200a000 r8:c0100224 r7:00000034 r6:bef86840 r5:00000001
[ 1946.881914]  r4:bef867a0
[ 1946.888793] ---[ end trace 7387f2a9725b28d0 ]---

---
 drivers/usb/gadget/function/f_fs.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

@@ -1476,11 +1476,15 @@ static void ffs_data_clear(struct ffs_da
 
 	BUG_ON(ffs->gadget);
 
-	if (ffs->epfiles)
+	if (ffs->epfiles) {
 		ffs_epfiles_destroy(ffs->epfiles, ffs->eps_count);
+		ffs->epfiles = NULL;
+	}
 
-	if (ffs->ffs_eventfd)
+	if (ffs->ffs_eventfd) {
 		eventfd_ctx_put(ffs->ffs_eventfd);
+		ffs->ffs_eventfd = NULL;
+	}
 
 	kfree(ffs->raw_descs_data);
 	kfree(ffs->raw_strings);

@@ -1493,7 +1497,6 @@ static void ffs_data_reset(struct ffs_da
 
 	ffs_data_clear(ffs);
 
-	ffs->epfiles = NULL;
 	ffs->raw_descs_data = NULL;
 	ffs->raw_descs = NULL;
 	ffs->raw_strings = NULL;

From: Alexey Makhalov <[email protected]>

commit 142c779d05d1fef75134c3cb63f52ccbc96d9e1f upstream.

The PVSCSI implementation in the VMware hypervisor under specific configuration ("SCSI Bus Sharing" set to "Physical") returns zero dataLen in the completion descriptor for READ CAPACITY(16). As a result, the kernel can not detect proper disk geometry. This can be recognized by the kernel message:

  [ 0.776588] sd 1:0:0:0: [sdb] Sector size 0 reported, assuming 512.

The PVSCSI implementation in QEMU does not set dataLen at all, keeping it zeroed. This leads to a boot hang as was reported by Shmulik Ladkani.

It is likely that the controller returns the garbage at the end of the buffer. Residual length should be set by the driver in that case. The SCSI layer will erase corresponding data. See commit bdb2b8cab439 ("[SCSI] erase invalid data returned by device") for details.

Commit e662502b3a78 ("scsi: vmw_pvscsi: Set correct residual data length") introduced the issue by setting residual length unconditionally, causing the SCSI layer to erase the useful payload beyond dataLen when this value is returned as 0.

As a result, considering existing issues in implementations of PVSCSI controllers, we do not want to call scsi_set_resid() when dataLen ==
0. Calling scsi_set_resid() has no effect if dataLen equals buffer length.

---
 drivers/scsi/vmw_pvscsi.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

@@ -562,9 +562,12 @@ static void pvscsi_complete_request(stru
 			 * Commands like INQUIRY may transfer less data than
 			 * requested by the initiator via bufflen. Set residual
 			 * count to make upper layer aware of the actual amount
-			 * of data returned.
+			 * of data returned. There are cases when controller
+			 * returns zero dataLen with non zero data - do not set
+			 * residual count in that case.
 			 */
-			scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen);
+			if (e->dataLen && (e->dataLen < scsi_bufflen(cmd)))
+				scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen);
 			cmd->result = (DID_OK << 16);
 			break;
 

From: Pavel Skripkin <[email protected]>

commit 9f3ccdc3f6ef10084ceb3a47df0961bec6196fd0 upstream.

Syzbot has reported warning in __flush_work(). This warning is caused by work->func == NULL, which means missing work initialization.

This may happen, since input_dev->close() calls cancel_work_sync(&dev->work), but dev->work initalization happens _after_ input_register_device() call.

So this patch moves dev->work initialization before registering input device

---
 drivers/input/mouse/appletouch.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -929,6 +929,8 @@ static int atp_probe(struct usb_interfac
 	set_bit(BTN_TOOL_TRIPLETAP, input_dev->keybit);
 	set_bit(BTN_LEFT, input_dev->keybit);
 
+	INIT_WORK(&dev->work, atp_reinit);
+
 	error = input_register_device(dev->input);
 	if (error)
 		goto err_free_buffer;

@@ -936,8 +938,6 @@ static int atp_probe(struct usb_interfac
 	/* save our data pointer in this interface device */
 	usb_set_intfdata(iface, dev);
 
-	INIT_WORK(&dev->work, atp_reinit);
-
 	return 0;
 
  err_free_buffer:

From: Leo L. Schwab <[email protected]>

commit bc7ec91718c49d938849697cfad98fcd9877cc26 upstream.

The spaceball.c module was not properly parsing the movement reports coming from the device. The code read axis data as signed 16-bit little-endian values starting at offset 2.

In fact, axis data in Spaceball movement reports are signed 16-bit big-endian values starting at offset 3. This was determined first by visually inspecting the data packets, and later verified by consulting:
http://spacemice.org/pdf/SpaceBall_2003-3003_Protocol.pdf

If this ever worked properly, it was in the time before Git...

---
 drivers/input/joystick/spaceball.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

@@ -35,6 +35,7 @@
 #include <linux/module.h>
 #include <linux/input.h>
 #include <linux/serio.h>
+#include <asm/unaligned.h>
 
 #define DRIVER_DESC	"SpaceTec SpaceBall 2003/3003/4000 FLX driver"
 

@@ -91,9 +92,15 @@ static void spaceball_process_packet(str
 
 		case 'D':					/* Ball data */
 			if (spaceball->idx != 15) return;
-			for (i = 0; i < 6; i++)
+			/*
+			 * Skip first three bytes; read six axes worth of data.
+			 * Axis values are signed 16-bit big-endian.
+			 */
+			data += 3;
+			for (i = 0; i < ARRAY_SIZE(spaceball_axes); i++) {
 				input_report_abs(dev, spaceball_axes[i],
-					(__s16)((data[2 * i + 3] << 8) | data[2 * i + 2]));
+					(__s16)get_unaligned_be16(&data[i * 2]));
+			}
 			break;
 
 		case 'K':					/* Button data */

From: Muchun Song <[email protected]>

commit e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0 upstream.

A real world panic issue was found as follow in Linux 5.4.

    BUG: unable to handle page fault for address: ffffde49a863de28
    PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0
    RIP: 0010:tw_timer_handler+0x20/0x40
    Call Trace:
     <IRQ>
     call_timer_fn+0x2b/0x120
     run_timer_softirq+0x1ef/0x450
     __do_softirq+0x10d/0x2b8
     irq_exit+0xc7/0xd0
     smp_apic_timer_interrupt+0x68/0x120
     apic_timer_interrupt+0xf/0x20

This issue was also reported since 2017 in the thread [1], unfortunately, the issue was still can be reproduced after fixing DCCP.

The ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net namespace is destroyed since tcp_sk_ops is registered befrore ipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops in the list of pernet_list. There will be a use-after-free on net->mib.net_statistics in tw_timer_handler after ipv4_mib_exit_net if there are some inflight time-wait timers.

This bug is not introduced by commit f2bf415cfed7 ("mib: add net to NET_ADD_STATS_BH") since the net_statistics is a global variable instead of dynamic allocation and freeing. Actually, commit 61a7e26028b9 ("mib: put net statistics on struct net") introduces the bug since it put net statistics on struct net and free it when net namespace is destroyed.

Moving init_ipv4_mibs() to the front of tcp_init() to fix this bug and replace pr_crit() with panic() since continuing is meaningless when init_ipv4_mibs() fails.

[1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1

---
 net/ipv4/af_inet.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

@@ -1770,6 +1770,10 @@ static int __init inet_init(void)
 
 	tcp_v4_init();
 
+	/* Initialise per-cpu ipv4 mibs */
+	if (init_ipv4_mibs())
+		panic("%s: Cannot init ipv4 mibs\n", __func__);
+
 	/* Setup TCP slab cache for open requests. */
 	tcp_init();
 

@@ -1798,12 +1802,6 @@ static int __init inet_init(void)
 
 	if (init_inet_pernet_ops())
 		pr_crit("%s: Cannot init ipv4 inet pernet ops\n", __func__);
-	/*
-	 *	Initialise per-cpu ipv4 mibs
-	 */
-
-	if (init_ipv4_mibs())
-		pr_crit("%s: Cannot init ipv4 mibs\n", __func__);
 
 	ipv4_proc_init();
 

Hi!

CIP testing did not find any problems here:

https://gitlab.com/cip-project/cip-testing/linux-stable-rc-ci/-/tree/linux-4.4.y

Best regards,
Pavel

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

Build results:

	total: 160 pass: 160 fail: 0
Qemu test results:
	total: 339 pass: 339 fail: 0

Guenter

All tests passing for Tegra ...

Test results for stable-v4.4:

    6 builds:	6 pass, 0 fail
    12 boots:	12 pass, 0 fail
    30 tests:	30 pass, 0 fail

Linux version: 4.4.298-rc1-ga1c4d899b501
Boards tested: tegra124-jetson-tk1, tegra20-ventana,

                tegra30-cardhu-a04

Jon

Results from Linaro’s test farm.
No regressions on arm64, arm, x86_64, and i386.

## Build
* kernel: 4.4.298-rc1
* git: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
* git branch: linux-4.4.y
* git commit: a1c4d899b5013233346ba4f33d952c391f0fe7fb
* git describe: v4.4.297-12-ga1c4d899b501
* test details:
https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-4.4.y/build/v4.4.297-12-ga1c4d899b501

## Test Regressions (compared to v4.4.297)
No test regressions found.

## Metric Regressions (compared to v4.4.297)
No metric regressions found.

## Test Fixes (compared to v4.4.297)
No test fixes found.

## Metric Fixes (compared to v4.4.297)
No metric fixes found.

## Test result summary
total: 32658, pass: 26026, fail: 62, skip: 5888, xfail: 682

## Build Summary
* arm: 129 total, 129 passed, 0 failed
* arm64: 31 total, 31 passed, 0 failed
* i386: 18 total, 18 passed, 0 failed
* juno-r2: 1 total, 1 passed, 0 failed
* mips: 22 total, 22 passed, 0 failed
* sparc: 12 total, 12 passed, 0 failed
* x15: 1 total, 1 passed, 0 failed
* x86: 1 total, 1 passed, 0 failed
* x86_64: 30 total, 24 passed, 6 failed

## Test suites summary
* libhugetlbfs
* linux-log-parser
* ltp-cap_bounds-tests
* ltp-commands-tests
* ltp-containers-tests
* ltp-controllers-tests
* ltp-cpuhotplug-tests
* ltp-crypto-tests
* ltp-cve-tests
* ltp-dio-tests
* ltp-fcntl-locktests-tests
* ltp-filecaps-tests
* ltp-fs-tests
* ltp-fs_bind-tests
* ltp-fs_perms_simple-tests
* ltp-fsx-tests
* ltp-hugetlb-tests
* ltp-io-tests
* ltp-ipc-tests
* ltp-math-tests
* ltp-mm-tests
* ltp-nptl-tests
* ltp-pty-tests
* ltp-sched-tests
* ltp-securebits-tests
* ltp-syscalls-tests
* ltp-tracing-tests
* packetdrill
* v4l2-compliance

--
Linaro LKFT
https://lkft.linaro.org

Compiled and booted on my test system. No dmesg regressions.

thanks,
-- Shuah