[PATCH 5.8 173/186] mm: track page table modifications in __apply_to_page_range()
From: Greg Kroah-Hartman
Date: Tue Sep 08 2020 - 14:25:21 EST
From: Joerg Roedel <jroedel@xxxxxxx>
commit e80d3909be42f7e38cc350c1ba109cf0aa51956a upstream.
__apply_to_page_range() is also used to change and/or allocate
page-table pages in the vmalloc area of the address space. Make sure
these changes get synchronized to other page-tables in the system by
calling arch_sync_kernel_mappings() when necessary.
The impact appears limited to x86-32, where apply_to_page_range may miss
updating the PMD. That leads to explosions in drivers like
BUG: unable to handle page fault for address: fe036000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
*pde = 00000000
Oops: 0002 [#1] SMP
CPU: 3 PID: 1300 Comm: gem_concurrent_ Not tainted 5.9.0-rc1+ #16
Hardware name: /NUC6i3SYB, BIOS SYSKLi35.86A.0024.2015.1027.2142 10/27/2015
EIP: __execlists_context_alloc+0x132/0x2d0 [i915]
Code: 31 d2 89 f0 e8 2f 55 02 00 89 45 e8 3d 00 f0 ff ff 0f 87 11 01 00 00 8b 4d e8 03 4b 30 b8 5a 5a 5a 5a ba 01 00 00 00 8d 79 04 <c7> 01 5a 5a 5a 5a c7 81 fc 0f 00 00 5a 5a 5a 5a 83 e7 fc 29 f9 81
EAX: 5a5a5a5a EBX: f60ca000 ECX: fe036000 EDX: 00000001
ESI: f43b7340 EDI: fe036004 EBP: f6389cb8 ESP: f6389c9c
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010286
CR0: 80050033 CR2: fe036000 CR3: 2d361000 CR4: 001506d0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: fffe0ff0 DR7: 00000400
Call Trace:
execlists_context_alloc+0x10/0x20 [i915]
intel_context_alloc_state+0x3f/0x70 [i915]
__intel_context_do_pin+0x117/0x170 [i915]
i915_gem_do_execbuffer+0xcc7/0x2500 [i915]
i915_gem_execbuffer2_ioctl+0xcd/0x1f0 [i915]
drm_ioctl_kernel+0x8f/0xd0
drm_ioctl+0x223/0x3d0
__ia32_sys_ioctl+0x1ab/0x760
__do_fast_syscall_32+0x3f/0x70
do_fast_syscall_32+0x29/0x60
do_SYSENTER_32+0x15/0x20
entry_SYSENTER_32+0x9f/0xf2
EIP: 0xb7f28559
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d 76 00 58 b8 77 00 00 00 cd 80 90 8d 76
EAX: ffffffda EBX: 00000005 ECX: c0406469 EDX: bf95556c
ESI: b7e68000 EDI: c0406469 EBP: 00000005 ESP: bf9554d8
DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000296
Modules linked in: i915 x86_pkg_temp_thermal intel_powerclamp crc32_pclmul crc32c_intel intel_cstate intel_uncore intel_gtt drm_kms_helper intel_pch_thermal video button autofs4 i2c_i801 i2c_smbus fan
CR2: 00000000fe036000
It looks like kasan, xen and i915 are vulnerable.
Actual impact is "on thinkpad X60 in 5.9-rc1, screen starts blinking
after 30-or-so minutes, and machine is unusable"
[sfr@xxxxxxxxxxxxxxxx: ARCH_PAGE_TABLE_SYNC_MASK needs vmalloc.h]
Link: https://lkml.kernel.org/r/20200825172508.16800a4f@xxxxxxxxxxxxxxxx
[chris@xxxxxxxxxxxxxxxxxx: changelog addition]
[pavel@xxxxxx: changelog addition]
Fixes: 2ba3e6947aed ("mm/vmalloc: track which page-table levels were modified")
Fixes: 86cf69f1d893 ("x86/mm/32: implement arch_sync_kernel_mappings()")
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Tested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> [x86-32]
Tested-by: Pavel Machek <pavel@xxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.8+]
Link: https://lkml.kernel.org/r/20200821123746.16904-1-joro@xxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 36 +++++++++++++++++++++++-------------
1 file changed, 23 insertions(+), 13 deletions(-)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -71,6 +71,7 @@
#include <linux/dax.h>
#include <linux/oom.h>
#include <linux/numa.h>
+#include <linux/vmalloc.h>
#include <trace/events/kmem.h>
@@ -2201,7 +2202,8 @@ EXPORT_SYMBOL(vm_iomap_memory);
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data, bool create)
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
{
pte_t *pte;
int err = 0;
@@ -2209,7 +2211,7 @@ static int apply_to_pte_range(struct mm_
if (create) {
pte = (mm == &init_mm) ?
- pte_alloc_kernel(pmd, addr) :
+ pte_alloc_kernel_track(pmd, addr, mask) :
pte_alloc_map_lock(mm, pmd, addr, &ptl);
if (!pte)
return -ENOMEM;
@@ -2230,6 +2232,7 @@ static int apply_to_pte_range(struct mm_
break;
}
} while (addr += PAGE_SIZE, addr != end);
+ *mask |= PGTBL_PTE_MODIFIED;
arch_leave_lazy_mmu_mode();
@@ -2240,7 +2243,8 @@ static int apply_to_pte_range(struct mm_
static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data, bool create)
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
{
pmd_t *pmd;
unsigned long next;
@@ -2249,7 +2253,7 @@ static int apply_to_pmd_range(struct mm_
BUG_ON(pud_huge(*pud));
if (create) {
- pmd = pmd_alloc(mm, pud, addr);
+ pmd = pmd_alloc_track(mm, pud, addr, mask);
if (!pmd)
return -ENOMEM;
} else {
@@ -2259,7 +2263,7 @@ static int apply_to_pmd_range(struct mm_
next = pmd_addr_end(addr, end);
if (create || !pmd_none_or_clear_bad(pmd)) {
err = apply_to_pte_range(mm, pmd, addr, next, fn, data,
- create);
+ create, mask);
if (err)
break;
}
@@ -2269,14 +2273,15 @@ static int apply_to_pmd_range(struct mm_
static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data, bool create)
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
{
pud_t *pud;
unsigned long next;
int err = 0;
if (create) {
- pud = pud_alloc(mm, p4d, addr);
+ pud = pud_alloc_track(mm, p4d, addr, mask);
if (!pud)
return -ENOMEM;
} else {
@@ -2286,7 +2291,7 @@ static int apply_to_pud_range(struct mm_
next = pud_addr_end(addr, end);
if (create || !pud_none_or_clear_bad(pud)) {
err = apply_to_pmd_range(mm, pud, addr, next, fn, data,
- create);
+ create, mask);
if (err)
break;
}
@@ -2296,14 +2301,15 @@ static int apply_to_pud_range(struct mm_
static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
unsigned long addr, unsigned long end,
- pte_fn_t fn, void *data, bool create)
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
{
p4d_t *p4d;
unsigned long next;
int err = 0;
if (create) {
- p4d = p4d_alloc(mm, pgd, addr);
+ p4d = p4d_alloc_track(mm, pgd, addr, mask);
if (!p4d)
return -ENOMEM;
} else {
@@ -2313,7 +2319,7 @@ static int apply_to_p4d_range(struct mm_
next = p4d_addr_end(addr, end);
if (create || !p4d_none_or_clear_bad(p4d)) {
err = apply_to_pud_range(mm, p4d, addr, next, fn, data,
- create);
+ create, mask);
if (err)
break;
}
@@ -2326,8 +2332,9 @@ static int __apply_to_page_range(struct
void *data, bool create)
{
pgd_t *pgd;
- unsigned long next;
+ unsigned long start = addr, next;
unsigned long end = addr + size;
+ pgtbl_mod_mask mask = 0;
int err = 0;
if (WARN_ON(addr >= end))
@@ -2338,11 +2345,14 @@ static int __apply_to_page_range(struct
next = pgd_addr_end(addr, end);
if (!create && pgd_none_or_clear_bad(pgd))
continue;
- err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create);
+ err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create, &mask);
if (err)
break;
} while (pgd++, addr = next, addr != end);
+ if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
+ arch_sync_kernel_mappings(start, start + size);
+
return err;
}