* [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries
@ 2021-08-17 13:58 Mike Rapoport
2021-08-17 14:01 ` David Hildenbrand
0 siblings, 1 reply; 6+ messages in thread
From: Mike Rapoport @ 2021-08-17 13:58 UTC (permalink / raw)
To: x86
Cc: Andrew Morton, Andy Lutomirski, Dave Hansen, David Hildenbrand,
Ingo Molnar, Jiri Olsa, Mike Rapoport, Mike Rapoport,
Oscar Salvador, Peter Zijlstra, Thomas Gleixner, Borislav Petkov,
linux-kernel, linux-fsdevel
From: Mike Rapoport <rppt@linux.ibm.com>
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>
---
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 ddeaba947eb3..07b56e90db5d 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_none(*p4d) || !p4d_present(*p4d))
return 0;
pud = pud_offset(p4d, addr);
- if (pud_none(*pud))
+ if (pud_none(*pud) || !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_none(*pmd) || !pmd_present(*pmd))
return 0;
if (pmd_large(*pmd))
base-commit: 7c60610d476766e128cc4284bb6349732cbd6606
--
2.28.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries
2021-08-17 13:58 [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries Mike Rapoport
@ 2021-08-17 14:01 ` David Hildenbrand
2021-08-17 14:02 ` David Hildenbrand
2021-08-18 17:42 ` Mike Rapoport
0 siblings, 2 replies; 6+ messages in thread
From: David Hildenbrand @ 2021-08-17 14:01 UTC (permalink / raw)
To: Mike Rapoport, x86
Cc: Andrew Morton, Andy Lutomirski, Dave Hansen, Ingo Molnar,
Jiri Olsa, Mike Rapoport, Oscar Salvador, Peter Zijlstra,
Thomas Gleixner, Borislav Petkov, linux-kernel, linux-fsdevel
On 17.08.21 15:58, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
>
> 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.
Why not fix the setting code?
>
> Reported-by: Jiri Olsa <jolsa@redhat.com>
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.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 ddeaba947eb3..07b56e90db5d 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_none(*p4d) || !p4d_present(*p4d))
> return 0;
if (!p4d_present(*p4d))
return 0;
should be sufficient I think.
Same applies to the others.
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries
2021-08-17 14:01 ` David Hildenbrand
@ 2021-08-17 14:02 ` David Hildenbrand
2021-08-19 10:56 ` Mike Rapoport
2021-08-18 17:42 ` Mike Rapoport
1 sibling, 1 reply; 6+ messages in thread
From: David Hildenbrand @ 2021-08-17 14:02 UTC (permalink / raw)
To: Mike Rapoport, x86
Cc: Andrew Morton, Andy Lutomirski, Dave Hansen, Ingo Molnar,
Jiri Olsa, Mike Rapoport, Oscar Salvador, Peter Zijlstra,
Thomas Gleixner, Borislav Petkov, linux-kernel, linux-fsdevel
On 17.08.21 16:01, David Hildenbrand wrote:
> On 17.08.21 15:58, Mike Rapoport wrote:
>> From: Mike Rapoport <rppt@linux.ibm.com>
>>
>> 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.
>
> Why not fix the setting code?
>
>>
>> Reported-by: Jiri Olsa <jolsa@redhat.com>
>> Signed-off-by: Mike Rapoport <rppt@linux.ibm.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 ddeaba947eb3..07b56e90db5d 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_none(*p4d) || !p4d_present(*p4d))
>> return 0;
>
> if (!p4d_present(*p4d))
> return 0;
>
> should be sufficient I think.
>
> Same applies to the others.
>
>
Oh, and I forgot, can we come up with Fixes: and Cc: stable tags?
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries
2021-08-17 14:02 ` David Hildenbrand
@ 2021-08-19 10:56 ` Mike Rapoport
0 siblings, 0 replies; 6+ messages in thread
From: Mike Rapoport @ 2021-08-19 10:56 UTC (permalink / raw)
To: David Hildenbrand
Cc: x86, Andrew Morton, Andy Lutomirski, Dave Hansen, Ingo Molnar,
Jiri Olsa, Mike Rapoport, Oscar Salvador, Peter Zijlstra,
Thomas Gleixner, Borislav Petkov, linux-kernel, linux-fsdevel
On Tue, Aug 17, 2021 at 04:02:16PM +0200, David Hildenbrand wrote:
> On 17.08.21 16:01, David Hildenbrand wrote:
> > On 17.08.21 15:58, Mike Rapoport wrote:
> > > From: Mike Rapoport <rppt@linux.ibm.com>
> > >
> > > 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.
> >
> > Why not fix the setting code?
> >
> > >
> > > Reported-by: Jiri Olsa <jolsa@redhat.com>
> > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.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 ddeaba947eb3..07b56e90db5d 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_none(*p4d) || !p4d_present(*p4d))
> > > return 0;
> >
> > if (!p4d_present(*p4d))
> > return 0;
> >
> > should be sufficient I think.
> >
> > Same applies to the others.
>
> Oh, and I forgot, can we come up with Fixes: and Cc: stable tags?
I'll add cc: stable for v2. As for Fixes:, I cannot point to a particular
commit. Looking at 9a14aefc1d28 ("x86: cpa, fix lookup_address") it seems
that the same problem existed with kern_addr_valid() back in 2008 (2.6.24 -
26.25 timeframe), so the fix is relevant for all stable versions active
supported today.
OTOH, nobody reported it till this week... :-/
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries
2021-08-17 14:01 ` David Hildenbrand
2021-08-17 14:02 ` David Hildenbrand
@ 2021-08-18 17:42 ` Mike Rapoport
2021-08-18 18:02 ` David Hildenbrand
1 sibling, 1 reply; 6+ messages in thread
From: Mike Rapoport @ 2021-08-18 17:42 UTC (permalink / raw)
To: David Hildenbrand
Cc: x86, Andrew Morton, Andy Lutomirski, Dave Hansen, Ingo Molnar,
Jiri Olsa, Mike Rapoport, Oscar Salvador, Peter Zijlstra,
Thomas Gleixner, Borislav Petkov, linux-kernel, linux-fsdevel
On Tue, Aug 17, 2021 at 04:01:13PM +0200, David Hildenbrand wrote:
> On 17.08.21 15:58, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> >
> > 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.
>
> Why not fix the setting code?
Because I'm not sure it won't backfire in some other place.
Fixing kern_addr_valid() looks safe and easy for backporting.
> > Reported-by: Jiri Olsa <jolsa@redhat.com>
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.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 ddeaba947eb3..07b56e90db5d 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_none(*p4d) || !p4d_present(*p4d))
> > return 0;
>
> if (!p4d_present(*p4d))
> return 0;
>
> should be sufficient I think.
>
> Same applies to the others.
Agree.
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries
2021-08-18 17:42 ` Mike Rapoport
@ 2021-08-18 18:02 ` David Hildenbrand
0 siblings, 0 replies; 6+ messages in thread
From: David Hildenbrand @ 2021-08-18 18:02 UTC (permalink / raw)
To: Mike Rapoport
Cc: x86, Andrew Morton, Andy Lutomirski, Dave Hansen, Ingo Molnar,
Jiri Olsa, Mike Rapoport, Oscar Salvador, Peter Zijlstra,
Thomas Gleixner, Borislav Petkov, linux-kernel, linux-fsdevel
On 18.08.21 19:42, Mike Rapoport wrote:
> On Tue, Aug 17, 2021 at 04:01:13PM +0200, David Hildenbrand wrote:
>> On 17.08.21 15:58, Mike Rapoport wrote:
>>> From: Mike Rapoport <rppt@linux.ibm.com>
>>>
>>> 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.
>>
>> Why not fix the setting code?
>
> Because I'm not sure it won't backfire in some other place.
> Fixing kern_addr_valid() looks safe and easy for backporting.
Fair enough, however it's somewhat unexpected to find e.g., !pmd_none()
&& !pmd_entry() in the direct map -- where no such thing as swapping exists.
Anyhow, the x86 maintainers are the right people to make a call, I'm
happy as long as it's fixed.
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-08-19 10:56 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-17 13:58 [PATCH] x86/mm: fix kern_addr_valid to cope with existing but not present entries Mike Rapoport
2021-08-17 14:01 ` David Hildenbrand
2021-08-17 14:02 ` David Hildenbrand
2021-08-19 10:56 ` Mike Rapoport
2021-08-18 17:42 ` Mike Rapoport
2021-08-18 18:02 ` David Hildenbrand
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).