All of lore.kernel.org
 help / color / mirror / Atom feed
* FAILED: patch "[PATCH] x86/mm: Fix kern_addr_valid() to cope with existing but not" failed to apply to 4.4-stable tree
@ 2021-09-20  7:08 gregkh
  2021-09-20 12:03 ` Mike Rapoport
  0 siblings, 1 reply; 3+ messages in thread
From: gregkh @ 2021-09-20  7:08 UTC (permalink / raw)
  To: rppt, bp, dave.hansen, david, jolsa, stable; +Cc: stable


The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 34b1999da935a33be6239226bfa6cd4f704c5c88 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.ibm.com>
Date: Thu, 19 Aug 2021 16:27:17 +0300
Subject: [PATCH] x86/mm: Fix kern_addr_valid() to cope with existing but not
 present entries

Jiri Olsa reported a fault when running:

  # cat /proc/kallsyms | grep ksys_read
  ffffffff8136d580 T ksys_read
  # objdump -d --start-address=0xffffffff8136d580 --stop-address=0xffffffff8136d590 /proc/kcore

  /proc/kcore:     file format elf64-x86-64

  Segmentation fault

  general protection fault, probably for non-canonical address 0xf887ffcbff000: 0000 [#1] SMP PTI
  CPU: 12 PID: 1079 Comm: objdump Not tainted 5.14.0-rc5qemu+ #508
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-4.fc34 04/01/2014
  RIP: 0010:kern_addr_valid
  Call Trace:
   read_kcore
   ? rcu_read_lock_sched_held
   ? rcu_read_lock_sched_held
   ? rcu_read_lock_sched_held
   ? trace_hardirqs_on
   ? rcu_read_lock_sched_held
   ? lock_acquire
   ? lock_acquire
   ? rcu_read_lock_sched_held
   ? lock_acquire
   ? rcu_read_lock_sched_held
   ? rcu_read_lock_sched_held
   ? rcu_read_lock_sched_held
   ? lock_release
   ? _raw_spin_unlock
   ? __handle_mm_fault
   ? rcu_read_lock_sched_held
   ? lock_acquire
   ? rcu_read_lock_sched_held
   ? lock_release
   proc_reg_read
   ? vfs_read
   vfs_read
   ksys_read
   do_syscall_64
   entry_SYSCALL_64_after_hwframe

The fault happens because kern_addr_valid() dereferences existent but not
present PMD in the high kernel mappings.

Such PMDs are created when free_kernel_image_pages() frees regions larger
than 2Mb. In this case, a part of the freed memory is mapped with PMDs and
the set_memory_np_noalias() -> ... -> __change_page_attr() sequence will
mark the PMD as not present rather than wipe it completely.

Have kern_addr_valid() check whether higher level page table entries are
present before trying to dereference them to fix this issue and to avoid
similar issues in the future.

Stable backporting note:
------------------------

Note that the stable marking is for all active stable branches because
there could be cases where pagetable entries exist but are not valid -
see 9a14aefc1d28 ("x86: cpa, fix lookup_address"), for example. So make
sure to be on the safe side here and use pXY_present() accessors rather
than pXY_none() which could #GP when accessing pages in the direct map.

Also see:

  c40a56a7818c ("x86/mm/init: Remove freed kernel image areas from alias mapping")

for more info.

Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Cc: <stable@vger.kernel.org>	# 4.4+
Link: https://lkml.kernel.org/r/20210819132717.19358-1-rppt@kernel.org

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index ddeaba947eb3..879886c6cc53 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1433,18 +1433,18 @@ int kern_addr_valid(unsigned long addr)
 		return 0;
 
 	p4d = p4d_offset(pgd, addr);
-	if (p4d_none(*p4d))
+	if (!p4d_present(*p4d))
 		return 0;
 
 	pud = pud_offset(p4d, addr);
-	if (pud_none(*pud))
+	if (!pud_present(*pud))
 		return 0;
 
 	if (pud_large(*pud))
 		return pfn_valid(pud_pfn(*pud));
 
 	pmd = pmd_offset(pud, addr);
-	if (pmd_none(*pmd))
+	if (!pmd_present(*pmd))
 		return 0;
 
 	if (pmd_large(*pmd))


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: FAILED: patch "[PATCH] x86/mm: Fix kern_addr_valid() to cope with existing but not" failed to apply to 4.4-stable tree
  2021-09-20  7:08 FAILED: patch "[PATCH] x86/mm: Fix kern_addr_valid() to cope with existing but not" failed to apply to 4.4-stable tree gregkh
@ 2021-09-20 12:03 ` Mike Rapoport
  2021-09-20 12:11   ` Greg KH
  0 siblings, 1 reply; 3+ messages in thread
From: Mike Rapoport @ 2021-09-20 12:03 UTC (permalink / raw)
  To: gregkh; +Cc: bp, dave.hansen, david, jolsa, stable

Hi Greg,

On Mon, Sep 20, 2021 at 09:08:35AM +0200, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

The version below applies to both v4.4 and v4.9:

From 997cc522b7c683ed13a8a4e44672fe4164b7d611 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.ibm.com>
Date: Thu, 19 Aug 2021 16:27:17 +0300
Subject: [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries

Jiri Olsa reported a fault when running:

	# cat /proc/kallsyms | grep ksys_read
	ffffffff8136d580 T ksys_read
	# objdump -d --start-address=0xffffffff8136d580 --stop-address=0xffffffff8136d590 /proc/kcore

	/proc/kcore:     file format elf64-x86-64

	Segmentation fault

krava33 login: [   68.330612] general protection fault, probably for non-canonical address 0xf887ffcbff000: 0000 [#1] SMP PTI
[   68.333118] CPU: 12 PID: 1079 Comm: objdump Not tainted 5.14.0-rc5qemu+ #508
[   68.334922] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-4.fc34 04/01/2014
[   68.336945] RIP: 0010:kern_addr_valid+0x150/0x300
[   68.338082] Code: 1f 40 00 48 8b 0d e8 12 61 01 48 85 f6 0f 85 ca 00 00 00 48 81 e1 00 f0 ff ff 48 21 c1 48 b8 00 00 00 00 80 88 ff ff 48 01 ca <48> 8b 3c 02 48 f7 c7 9f ff ff ff 0f 84 d8 fe ff ff 48 89 f8 0f 1f
[   68.342220] RSP: 0018:ffffc90000bcbc38 EFLAGS: 00010206
[   68.343428] RAX: ffff888000000000 RBX: 0000000000001000 RCX: 000ffffffcbff000
[   68.345029] RDX: 000ffffffcbff000 RSI: 0000000000000000 RDI: 800ffffffcbff062
[   68.346599] RBP: ffffc90000bcbea8 R08: 0000000000001000 R09: 0000000000000000
[   68.349000] R10: 0000000000000000 R11: 0000000000001000 R12: 00007fcc0fd80010
[   68.350804] R13: ffffffff83400000 R14: 0000000000400000 R15: ffffffff843d23e0
[   68.352609] FS:  00007fcc111fcc80(0000) GS:ffff888275e00000(0000) knlGS:0000000000000000
[   68.354638] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   68.356104] CR2: 00007fcc0fd80000 CR3: 000000011226e004 CR4: 0000000000770ee0
[   68.357896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   68.359694] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   68.361597] PKRU: 55555554
[   68.362460] Call Trace:
[   68.363252]  read_kcore+0x57f/0x920
[   68.364289]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.365630]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.366955]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.368277]  ? trace_hardirqs_on+0x1b/0xd0
[   68.369462]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.370793]  ? lock_acquire+0x195/0x2f0
[   68.371920]  ? lock_acquire+0x195/0x2f0
[   68.373035]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.374364]  ? lock_acquire+0x195/0x2f0
[   68.375498]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.376831]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.379883]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.381268]  ? lock_release+0x22b/0x3e0
[   68.382458]  ? _raw_spin_unlock+0x1f/0x30
[   68.383685]  ? __handle_mm_fault+0xcfc/0x15f0
[   68.384994]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.386389]  ? lock_acquire+0x195/0x2f0
[   68.387573]  ? rcu_read_lock_sched_held+0x12/0x80
[   68.388969]  ? lock_release+0x22b/0x3e0
[   68.390145]  proc_reg_read+0x55/0xa0
[   68.391257]  ? vfs_read+0x78/0x1b0
[   68.392336]  vfs_read+0xa7/0x1b0
[   68.393328]  ksys_read+0x68/0xe0
[   68.394308]  do_syscall_64+0x3b/0x90
[   68.395391]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   68.396804] RIP: 0033:0x7fcc11cf92e2
[   68.397824] Code: c0 e9 b2 fe ff ff 50 48 8d 3d ea 2e 0a 00 e8 95 e9 01 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24
[   68.402420] RSP: 002b:00007ffd6e0f8da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   68.404357] RAX: ffffffffffffffda RBX: 0000565439305b20 RCX: 00007fcc11cf92e2
[   68.406061] RDX: 0000000000800000 RSI: 00007fcc0f980010 RDI: 0000000000000003
[   68.407747] RBP: 00007fcc11dcd300 R08: 0000000000000003 R09: 00007fcc0d980010
[   68.410937] R10: 0000000003826000 R11: 0000000000000246 R12: 00007fcc0f980010
[   68.412624] R13: 0000000000000d68 R14: 00007fcc11dcc700 R15: 0000000000800000
[   68.414322] Modules linked in: intel_rapl_msr intel_rapl_common nfit kvm_intel kvm irqbypass rapl iTCO_wdt iTCO_vendor_support i2c_i801 i2c_smbus lpc_ich drm drm_panel_orientation_quirks zram xfs crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel
[   68.419591] ---[ end trace e2c30f827226966b ]---
[   68.420969] RIP: 0010:kern_addr_valid+0x150/0x300
[   68.422308] Code: 1f 40 00 48 8b 0d e8 12 61 01 48 85 f6 0f 85 ca 00 00 00 48 81 e1 00 f0 ff ff 48 21 c1 48 b8 00 00 00 00 80 88 ff ff 48 01 ca <48> 8b 3c 02 48 f7 c7 9f ff ff ff 0f 84 d8 fe ff ff 48 89 f8 0f 1f
[   68.426826] RSP: 0018:ffffc90000bcbc38 EFLAGS: 00010206
[   68.428150] RAX: ffff888000000000 RBX: 0000000000001000 RCX: 000ffffffcbff000
[   68.429813] RDX: 000ffffffcbff000 RSI: 0000000000000000 RDI: 800ffffffcbff062
[   68.431465] RBP: ffffc90000bcbea8 R08: 0000000000001000 R09: 0000000000000000
[   68.433115] R10: 0000000000000000 R11: 0000000000001000 R12: 00007fcc0fd80010
[   68.434768] R13: ffffffff83400000 R14: 0000000000400000 R15: ffffffff843d23e0
[   68.436423] FS:  00007fcc111fcc80(0000) GS:ffff888275e00000(0000) knlGS:0000000000000000
[   68.438354] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   68.442077] CR2: 00007fcc0fd80000 CR3: 000000011226e004 CR4: 0000000000770ee0
[   68.443727] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   68.445370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   68.447010] PKRU: 55555554

The fault happens because kern_addr_valid() dereferences existent but not
present PMD in the high kernel mappings.

Such PMDs are created when free_kernel_image_pages() frees regions larger
than 2Mb. In this case a part of the freed memory is mapped with PMDs and
the set_memory_np_noalias() -> ... -> __change_page_attr() sequence will
mark the PMD as not present rather than wipe it completely.

Make kern_addr_valid() to check whether higher level page table entries are
present before trying to dereference them to fix this issue and to avoid
similar issues in the future.

Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: <stable@vger.kernel.org>	# 4.4+
Tested-by: Jiri Olsa <jolsa@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
---
 arch/x86/mm/init_64.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index d76ec9348cff..547d80fc76d7 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1182,21 +1182,21 @@ int kern_addr_valid(unsigned long addr)
 		return 0;
 
 	pud = pud_offset(pgd, addr);
-	if (pud_none(*pud))
+	if (!pud_present(*pud))
 		return 0;
 
 	if (pud_large(*pud))
 		return pfn_valid(pud_pfn(*pud));
 
 	pmd = pmd_offset(pud, addr);
-	if (pmd_none(*pmd))
+	if (!pmd_present(*pmd))
 		return 0;
 
 	if (pmd_large(*pmd))
 		return pfn_valid(pmd_pfn(*pmd));
 
 	pte = pte_offset_kernel(pmd, addr);
-	if (pte_none(*pte))
+	if (!pte_present(*pte))
 		return 0;
 
 	return pfn_valid(pte_pfn(*pte));
-- 
2.28.0

 

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: FAILED: patch "[PATCH] x86/mm: Fix kern_addr_valid() to cope with existing but not" failed to apply to 4.4-stable tree
  2021-09-20 12:03 ` Mike Rapoport
@ 2021-09-20 12:11   ` Greg KH
  0 siblings, 0 replies; 3+ messages in thread
From: Greg KH @ 2021-09-20 12:11 UTC (permalink / raw)
  To: Mike Rapoport; +Cc: bp, dave.hansen, david, jolsa, stable

On Mon, Sep 20, 2021 at 03:03:14PM +0300, Mike Rapoport wrote:
> Hi Greg,
> 
> On Mon, Sep 20, 2021 at 09:08:35AM +0200, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 4.4-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> 
> The version below applies to both v4.4 and v4.9:

Now queued up, thanks.

greg k-h

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-09-20 12:11 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-20  7:08 FAILED: patch "[PATCH] x86/mm: Fix kern_addr_valid() to cope with existing but not" failed to apply to 4.4-stable tree gregkh
2021-09-20 12:03 ` Mike Rapoport
2021-09-20 12:11   ` Greg KH

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.