cve/published/2024/CVE-2024-57979.mbox - pub/scm/linux/security/vulns - Git at Google

 From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
 From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 To: <linux-cve-announce@vger.kernel.org>
 Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
 Subject: CVE-2024-57979: pps: Fix a use-after-free

 Description
 ===========

 In the Linux kernel, the following vulnerability has been resolved:

 pps: Fix a use-after-free

 On a board running ntpd and gpsd, I'm seeing a consistent use-after-free
 in sys_exit() from gpsd when rebooting:

     pps pps1: removed
     ------------[ cut here ]------------
     kobject: '(null)' (00000000db4bec24): is not initialized, yet kobject_put() is being called.
     WARNING: CPU: 2 PID: 440 at lib/kobject.c:734 kobject_put+0x120/0x150
     CPU: 2 UID: 299 PID: 440 Comm: gpsd Not tainted 6.11.0-rc6-00308-gb31c44928842 #1
     Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
     pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
     pc : kobject_put+0x120/0x150
     lr : kobject_put+0x120/0x150
     sp : ffffffc0803d3ae0
     x29: ffffffc0803d3ae0 x28: ffffff8042dc9738 x27: 0000000000000001
     x26: 0000000000000000 x25: ffffff8042dc9040 x24: ffffff8042dc9440
     x23: ffffff80402a4620 x22: ffffff8042ef4bd0 x21: ffffff80405cb600
     x20: 000000000008001b x19: ffffff8040b3b6e0 x18: 0000000000000000
     x17: 0000000000000000 x16: 0000000000000000 x15: 696e6920746f6e20
     x14: 7369203a29343263 x13: 205d303434542020 x12: 0000000000000000
     x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
     x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
     x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
     x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
     Call trace:
      kobject_put+0x120/0x150
      cdev_put+0x20/0x3c
      __fput+0x2c4/0x2d8
      ____fput+0x1c/0x38
      task_work_run+0x70/0xfc
      do_exit+0x2a0/0x924
      do_group_exit+0x34/0x90
      get_signal+0x7fc/0x8c0
      do_signal+0x128/0x13b4
      do_notify_resume+0xdc/0x160
      el0_svc+0xd4/0xf8
      el0t_64_sync_handler+0x140/0x14c
      el0t_64_sync+0x190/0x194
     ---[ end trace 0000000000000000 ]---

 ...followed by more symptoms of corruption, with similar stacks:

     refcount_t: underflow; use-after-free.
     kernel BUG at lib/list_debug.c:62!
     Kernel panic - not syncing: Oops - BUG: Fatal exception

 This happens because pps_device_destruct() frees the pps_device with the
 embedded cdev immediately after calling cdev_del(), but, as the comment
 above cdev_del() notes, fops for previously opened cdevs are still
 callable even after cdev_del() returns. I think this bug has always
 been there: I can't explain why it suddenly started happening every time
 I reboot this particular board.

 In commit d953e0e837e6 ("pps: Fix a use-after free bug when
 unregistering a source."), George Spelvin suggested removing the
 embedded cdev. That seems like the simplest way to fix this, so I've
 implemented his suggestion, using __register_chrdev() with pps_idr
 becoming the source of truth for which minor corresponds to which
 device.

 But now that pps_idr defines userspace visibility instead of cdev_add(),
 we need to be sure the pps->dev refcount can't reach zero while
 userspace can still find it again. So, the idr_remove() call moves to
 pps_unregister_cdev(), and pps_idr now holds a reference to pps->dev.

     pps_core: source serial1 got cdev (251:1)
     <...>
     pps pps1: removed
     pps_core: unregistering pps1
     pps_core: deallocating pps1

 The Linux kernel CVE team has assigned CVE-2024-57979 to this issue.


 Affected and fixed versions
 ===========================

 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 5.4.291 with commit 785c78ed0d39d1717cca3ef931d3e51337b5e90e
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 5.10.235 with commit 1a7735ab2cb9747518a7416fb5929e85442dec62
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 5.15.179 with commit c4041b6b0a7a3def8cf3f3d6120ff337bc4c40f7
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.1.129 with commit 91932db1d96b2952299ce30c1c693d834d10ace6
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.6.76 with commit cd3bbcb6b3a7caa5ce67de76723b6d8531fb7f64
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.12.13 with commit 7e5ee3281dc09014367f5112b6d566ba36ea2d49
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.13.2 with commit 85241f7de216f8298f6e48540ea13d7dcd100870
 	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.14 with commit c79a39dc8d060b9e64e8b0fa9d245d44befeefbe
 	Issue introduced in 3.2.40 with commit 77327a71f9841b7dfa708195d1cb133d4ef4a989
 	Issue introduced in 3.4.87 with commit cd59fb14918a6b20c1ac8be121fa6397b97b00cb
 	Issue introduced in 3.8.1 with commit 49626fbb0360332e40fd76a48cb2ba876d6134ad

 Please see https://www.kernel.org for a full list of currently supported
 kernel versions by the kernel community.

 Unaffected versions might change over time as fixes are backported to
 older supported kernel versions.  The official CVE entry at
 	https://cve.org/CVERecord/?id=CVE-2024-57979
 will be updated if fixes are backported, please check that for the most
 up to date information about this issue.


 Affected files
 ==============

 The file(s) affected by this issue are:
 	drivers/pps/clients/pps-gpio.c
 	drivers/pps/clients/pps-ktimer.c
 	drivers/pps/clients/pps-ldisc.c
 	drivers/pps/clients/pps_parport.c
 	drivers/pps/kapi.c
 	drivers/pps/kc.c
 	drivers/pps/pps.c
 	drivers/ptp/ptp_ocp.c
 	include/linux/pps_kernel.h


 Mitigation
 ==========

 The Linux kernel CVE team recommends that you update to the latest
 stable kernel version for this, and many other bugfixes.  Individual
 changes are never tested alone, but rather are part of a larger kernel
 release.  Cherry-picking individual commits is not recommended or
 supported by the Linux kernel community at all.  If however, updating to
 the latest release is impossible, the individual changes to resolve this
 issue can be found at these commits:
 	https://git.kernel.org/stable/c/785c78ed0d39d1717cca3ef931d3e51337b5e90e
 	https://git.kernel.org/stable/c/1a7735ab2cb9747518a7416fb5929e85442dec62
 	https://git.kernel.org/stable/c/c4041b6b0a7a3def8cf3f3d6120ff337bc4c40f7
 	https://git.kernel.org/stable/c/91932db1d96b2952299ce30c1c693d834d10ace6
 	https://git.kernel.org/stable/c/cd3bbcb6b3a7caa5ce67de76723b6d8531fb7f64
 	https://git.kernel.org/stable/c/7e5ee3281dc09014367f5112b6d566ba36ea2d49
 	https://git.kernel.org/stable/c/85241f7de216f8298f6e48540ea13d7dcd100870
 	https://git.kernel.org/stable/c/c79a39dc8d060b9e64e8b0fa9d245d44befeefbe
	From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
	From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
	To: <linux-cve-announce@vger.kernel.org>
	Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
	Subject: CVE-2024-57979: pps: Fix a use-after-free

	Description
	===========

	In the Linux kernel, the following vulnerability has been resolved:

	pps: Fix a use-after-free

	On a board running ntpd and gpsd, I'm seeing a consistent use-after-free
	in sys_exit() from gpsd when rebooting:

	pps pps1: removed
	------------[ cut here ]------------
	kobject: '(null)' (00000000db4bec24): is not initialized, yet kobject_put() is being called.
	WARNING: CPU: 2 PID: 440 at lib/kobject.c:734 kobject_put+0x120/0x150
	CPU: 2 UID: 299 PID: 440 Comm: gpsd Not tainted 6.11.0-rc6-00308-gb31c44928842 #1
	Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
	pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
	pc : kobject_put+0x120/0x150
	lr : kobject_put+0x120/0x150
	sp : ffffffc0803d3ae0
	x29: ffffffc0803d3ae0 x28: ffffff8042dc9738 x27: 0000000000000001
	x26: 0000000000000000 x25: ffffff8042dc9040 x24: ffffff8042dc9440
	x23: ffffff80402a4620 x22: ffffff8042ef4bd0 x21: ffffff80405cb600
	x20: 000000000008001b x19: ffffff8040b3b6e0 x18: 0000000000000000
	x17: 0000000000000000 x16: 0000000000000000 x15: 696e6920746f6e20
	x14: 7369203a29343263 x13: 205d303434542020 x12: 0000000000000000
	x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
	x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
	x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
	x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
	Call trace:
	kobject_put+0x120/0x150
	cdev_put+0x20/0x3c
	__fput+0x2c4/0x2d8
	____fput+0x1c/0x38
	task_work_run+0x70/0xfc
	do_exit+0x2a0/0x924
	do_group_exit+0x34/0x90
	get_signal+0x7fc/0x8c0
	do_signal+0x128/0x13b4
	do_notify_resume+0xdc/0x160
	el0_svc+0xd4/0xf8
	el0t_64_sync_handler+0x140/0x14c
	el0t_64_sync+0x190/0x194
	---[ end trace 0000000000000000 ]---

	...followed by more symptoms of corruption, with similar stacks:

	refcount_t: underflow; use-after-free.
	kernel BUG at lib/list_debug.c:62!
	Kernel panic - not syncing: Oops - BUG: Fatal exception

	This happens because pps_device_destruct() frees the pps_device with the
	embedded cdev immediately after calling cdev_del(), but, as the comment
	above cdev_del() notes, fops for previously opened cdevs are still
	callable even after cdev_del() returns. I think this bug has always
	been there: I can't explain why it suddenly started happening every time
	I reboot this particular board.

	In commit d953e0e837e6 ("pps: Fix a use-after free bug when
	unregistering a source."), George Spelvin suggested removing the
	embedded cdev. That seems like the simplest way to fix this, so I've
	implemented his suggestion, using __register_chrdev() with pps_idr
	becoming the source of truth for which minor corresponds to which
	device.

	But now that pps_idr defines userspace visibility instead of cdev_add(),
	we need to be sure the pps->dev refcount can't reach zero while
	userspace can still find it again. So, the idr_remove() call moves to
	pps_unregister_cdev(), and pps_idr now holds a reference to pps->dev.

	pps_core: source serial1 got cdev (251:1)
	<...>
	pps pps1: removed
	pps_core: unregistering pps1
	pps_core: deallocating pps1

	The Linux kernel CVE team has assigned CVE-2024-57979 to this issue.


	Affected and fixed versions
	===========================

	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 5.4.291 with commit 785c78ed0d39d1717cca3ef931d3e51337b5e90e
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 5.10.235 with commit 1a7735ab2cb9747518a7416fb5929e85442dec62
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 5.15.179 with commit c4041b6b0a7a3def8cf3f3d6120ff337bc4c40f7
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.1.129 with commit 91932db1d96b2952299ce30c1c693d834d10ace6
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.6.76 with commit cd3bbcb6b3a7caa5ce67de76723b6d8531fb7f64
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.12.13 with commit 7e5ee3281dc09014367f5112b6d566ba36ea2d49
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.13.2 with commit 85241f7de216f8298f6e48540ea13d7dcd100870
	Issue introduced in 3.9 with commit d953e0e837e65ecc1ddaa4f9560f7925878a0de6 and fixed in 6.14 with commit c79a39dc8d060b9e64e8b0fa9d245d44befeefbe
	Issue introduced in 3.2.40 with commit 77327a71f9841b7dfa708195d1cb133d4ef4a989
	Issue introduced in 3.4.87 with commit cd59fb14918a6b20c1ac8be121fa6397b97b00cb
	Issue introduced in 3.8.1 with commit 49626fbb0360332e40fd76a48cb2ba876d6134ad

	Please see https://www.kernel.org for a full list of currently supported
	kernel versions by the kernel community.

	Unaffected versions might change over time as fixes are backported to
	older supported kernel versions. The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-57979
	will be updated if fixes are backported, please check that for the most
	up to date information about this issue.


	Affected files
	==============

	The file(s) affected by this issue are:
	drivers/pps/clients/pps-gpio.c
	drivers/pps/clients/pps-ktimer.c
	drivers/pps/clients/pps-ldisc.c
	drivers/pps/clients/pps_parport.c
	drivers/pps/kapi.c
	drivers/pps/kc.c
	drivers/pps/pps.c
	drivers/ptp/ptp_ocp.c
	include/linux/pps_kernel.h


	Mitigation
	==========

	The Linux kernel CVE team recommends that you update to the latest
	stable kernel version for this, and many other bugfixes. Individual
	changes are never tested alone, but rather are part of a larger kernel
	release. Cherry-picking individual commits is not recommended or
	supported by the Linux kernel community at all. If however, updating to
	the latest release is impossible, the individual changes to resolve this
	issue can be found at these commits:
	https://git.kernel.org/stable/c/785c78ed0d39d1717cca3ef931d3e51337b5e90e
	https://git.kernel.org/stable/c/1a7735ab2cb9747518a7416fb5929e85442dec62
	https://git.kernel.org/stable/c/c4041b6b0a7a3def8cf3f3d6120ff337bc4c40f7
	https://git.kernel.org/stable/c/91932db1d96b2952299ce30c1c693d834d10ace6
	https://git.kernel.org/stable/c/cd3bbcb6b3a7caa5ce67de76723b6d8531fb7f64
	https://git.kernel.org/stable/c/7e5ee3281dc09014367f5112b6d566ba36ea2d49
	https://git.kernel.org/stable/c/85241f7de216f8298f6e48540ea13d7dcd100870
	https://git.kernel.org/stable/c/c79a39dc8d060b9e64e8b0fa9d245d44befeefbe