* + arm-pgtable-fix-null-pointer-dereference-issue.patch added to mm-hotfixes-unstable branch
@ 2025-02-12 7:04 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2025-02-12 7:04 UTC (permalink / raw)
To: mm-commits, stable, ryan.roberts, muchun.song, linux, hughd, ezra,
david, zhengqi.arch, akpm
The patch titled
Subject: arm: pgtable: fix NULL pointer dereference issue
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
arm-pgtable-fix-null-pointer-dereference-issue.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm-pgtable-fix-null-pointer-dereference-issue.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Qi Zheng <zhengqi.arch@bytedance.com>
Subject: arm: pgtable: fix NULL pointer dereference issue
Date: Wed, 12 Feb 2025 14:40:02 +0800
When update_mmu_cache_range() is called by update_mmu_cache(), the vmf
parameter is NULL, which will cause a NULL pointer dereference issue in
adjust_pte():
Unable to handle kernel NULL pointer dereference at virtual address 00000030 when read
Hardware name: Atmel AT91SAM9
PC is at update_mmu_cache_range+0x1e0/0x278
LR is at pte_offset_map_rw_nolock+0x18/0x2c
Call trace:
update_mmu_cache_range from remove_migration_pte+0x29c/0x2ec
remove_migration_pte from rmap_walk_file+0xcc/0x130
rmap_walk_file from remove_migration_ptes+0x90/0xa4
remove_migration_ptes from migrate_pages_batch+0x6d4/0x858
migrate_pages_batch from migrate_pages+0x188/0x488
migrate_pages from compact_zone+0x56c/0x954
compact_zone from compact_node+0x90/0xf0
compact_node from kcompactd+0x1d4/0x204
kcompactd from kthread+0x120/0x12c
kthread from ret_from_fork+0x14/0x38
Exception stack(0xc0d8bfb0 to 0xc0d8bff8)
To fix it, do not rely on whether 'ptl' is equal to decide whether to hold
the pte lock, but decide it by whether CONFIG_SPLIT_PTE_PTLOCKS is
enabled. In addition, if two vmas map to the same PTE page, there is no
need to hold the pte lock again, otherwise a deadlock will occur. Just add
the need_lock parameter to let adjust_pte() know this information.
Link: https://lkml.kernel.org/r/20250212064002.55598-1-zhengqi.arch@bytedance.com
Fixes: fc9c45b71f43 ("arm: adjust_pte() use pte_offset_map_rw_nolock()")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reported-by: Ezra Buehler <ezra@easyb.ch>
Closes: https://lore.kernel.org/lkml/CAM1KZSmZ2T_riHvay+7cKEFxoPgeVpHkVFTzVVEQ1BO0cLkHEQ@mail.gmail.com/
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
arch/arm/mm/fault-armv.c | 40 +++++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 12 deletions(-)
--- a/arch/arm/mm/fault-armv.c~arm-pgtable-fix-null-pointer-dereference-issue
+++ a/arch/arm/mm/fault-armv.c
@@ -62,7 +62,7 @@ static int do_adjust_pte(struct vm_area_
}
static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
- unsigned long pfn, struct vm_fault *vmf)
+ unsigned long pfn, bool need_lock)
{
spinlock_t *ptl;
pgd_t *pgd;
@@ -99,12 +99,11 @@ again:
if (!pte)
return 0;
- /*
- * If we are using split PTE locks, then we need to take the page
- * lock here. Otherwise we are using shared mm->page_table_lock
- * which is already locked, thus cannot take it.
- */
- if (ptl != vmf->ptl) {
+ if (need_lock) {
+ /*
+ * Use nested version here to indicate that we are already
+ * holding one similar spinlock.
+ */
spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pmd)))) {
pte_unmap_unlock(pte, ptl);
@@ -114,7 +113,7 @@ again:
ret = do_adjust_pte(vma, address, pfn, pte);
- if (ptl != vmf->ptl)
+ if (need_lock)
spin_unlock(ptl);
pte_unmap(pte);
@@ -123,16 +122,17 @@ again:
static void
make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep, unsigned long pfn,
- struct vm_fault *vmf)
+ unsigned long addr, pte_t *ptep, unsigned long pfn)
{
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *mpnt;
unsigned long offset;
+ unsigned long start;
pgoff_t pgoff;
int aliases = 0;
pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
+ start = ALIGN_DOWN(addr, PMD_SIZE);
/*
* If we have any shared mappings that are in the same mm
@@ -141,6 +141,14 @@ make_coherent(struct address_space *mapp
*/
flush_dcache_mmap_lock(mapping);
vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
+ unsigned long mpnt_addr;
+ /*
+ * If we are using split PTE locks, then we need to take the pte
+ * lock. Otherwise we are using shared mm->page_table_lock which
+ * is already locked, thus cannot take it.
+ */
+ bool need_lock = IS_ENABLED(CONFIG_SPLIT_PTE_PTLOCKS);
+
/*
* If this VMA is not in our MM, we can ignore it.
* Note that we intentionally mask out the VMA
@@ -151,7 +159,15 @@ make_coherent(struct address_space *mapp
if (!(mpnt->vm_flags & VM_MAYSHARE))
continue;
offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
- aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn, vmf);
+ mpnt_addr = mpnt->vm_start + offset;
+ /*
+ * If mpnt_addr and addr are mapped to the same PTE page, there
+ * is no need to hold the pte lock again, otherwise a deadlock
+ * will occur.
+ */
+ if (mpnt_addr >= start && mpnt_addr - start < PMD_SIZE)
+ need_lock = false;
+ aliases += adjust_pte(mpnt, mpnt_addr, pfn, need_lock);
}
flush_dcache_mmap_unlock(mapping);
if (aliases)
@@ -194,7 +210,7 @@ void update_mmu_cache_range(struct vm_fa
__flush_dcache_folio(mapping, folio);
if (mapping) {
if (cache_is_vivt())
- make_coherent(mapping, vma, addr, ptep, pfn, vmf);
+ make_coherent(mapping, vma, addr, ptep, pfn);
else if (vma->vm_flags & VM_EXEC)
__flush_icache_all();
}
_
Patches currently in -mm which might be from zhengqi.arch@bytedance.com are
mm-pgtable-fix-incorrect-reclaim-of-non-empty-pte-pages.patch
arm-pgtable-fix-null-pointer-dereference-issue.patch
^ permalink raw reply [flat|nested] 2+ messages in thread* + arm-pgtable-fix-null-pointer-dereference-issue.patch added to mm-hotfixes-unstable branch
@ 2025-02-18 3:56 Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2025-02-18 3:56 UTC (permalink / raw)
To: mm-commits, stable, ryan.roberts, muchun.song, linux, hughd,
ezra.buehler, david, zhengqi.arch, akpm
The patch titled
Subject: arm: pgtable: fix NULL pointer dereference issue
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
arm-pgtable-fix-null-pointer-dereference-issue.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm-pgtable-fix-null-pointer-dereference-issue.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Qi Zheng <zhengqi.arch@bytedance.com>
Subject: arm: pgtable: fix NULL pointer dereference issue
Date: Mon, 17 Feb 2025 10:49:24 +0800
When update_mmu_cache_range() is called by update_mmu_cache(), the vmf
parameter is NULL, which will cause a NULL pointer dereference issue in
adjust_pte():
Unable to handle kernel NULL pointer dereference at virtual address 00000030 when read
Hardware name: Atmel AT91SAM9
PC is at update_mmu_cache_range+0x1e0/0x278
LR is at pte_offset_map_rw_nolock+0x18/0x2c
Call trace:
update_mmu_cache_range from remove_migration_pte+0x29c/0x2ec
remove_migration_pte from rmap_walk_file+0xcc/0x130
rmap_walk_file from remove_migration_ptes+0x90/0xa4
remove_migration_ptes from migrate_pages_batch+0x6d4/0x858
migrate_pages_batch from migrate_pages+0x188/0x488
migrate_pages from compact_zone+0x56c/0x954
compact_zone from compact_node+0x90/0xf0
compact_node from kcompactd+0x1d4/0x204
kcompactd from kthread+0x120/0x12c
kthread from ret_from_fork+0x14/0x38
Exception stack(0xc0d8bfb0 to 0xc0d8bff8)
To fix it, do not rely on whether 'ptl' is equal to decide whether to hold
the pte lock, but decide it by whether CONFIG_SPLIT_PTE_PTLOCKS is
enabled. In addition, if two vmas map to the same PTE page, there is no
need to hold the pte lock again, otherwise a deadlock will occur. Just
add the need_lock parameter to let adjust_pte() know this information.
Link: https://lkml.kernel.org/r/20250217024924.57996-1-zhengqi.arch@bytedance.com
Fixes: fc9c45b71f43 ("arm: adjust_pte() use pte_offset_map_rw_nolock()")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reported-by: Ezra Buehler <ezra.buehler@husqvarnagroup.com>
Closes: https://lore.kernel.org/lkml/CAM1KZSmZ2T_riHvay+7cKEFxoPgeVpHkVFTzVVEQ1BO0cLkHEQ@mail.gmail.com/
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
arch/arm/mm/fault-armv.c | 37 +++++++++++++++++++++++++------------
1 file changed, 25 insertions(+), 12 deletions(-)
--- a/arch/arm/mm/fault-armv.c~arm-pgtable-fix-null-pointer-dereference-issue
+++ a/arch/arm/mm/fault-armv.c
@@ -62,7 +62,7 @@ static int do_adjust_pte(struct vm_area_
}
static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
- unsigned long pfn, struct vm_fault *vmf)
+ unsigned long pfn, bool need_lock)
{
spinlock_t *ptl;
pgd_t *pgd;
@@ -99,12 +99,11 @@ again:
if (!pte)
return 0;
- /*
- * If we are using split PTE locks, then we need to take the page
- * lock here. Otherwise we are using shared mm->page_table_lock
- * which is already locked, thus cannot take it.
- */
- if (ptl != vmf->ptl) {
+ if (need_lock) {
+ /*
+ * Use nested version here to indicate that we are already
+ * holding one similar spinlock.
+ */
spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pmd)))) {
pte_unmap_unlock(pte, ptl);
@@ -114,7 +113,7 @@ again:
ret = do_adjust_pte(vma, address, pfn, pte);
- if (ptl != vmf->ptl)
+ if (need_lock)
spin_unlock(ptl);
pte_unmap(pte);
@@ -123,9 +122,10 @@ again:
static void
make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
- unsigned long addr, pte_t *ptep, unsigned long pfn,
- struct vm_fault *vmf)
+ unsigned long addr, pte_t *ptep, unsigned long pfn)
{
+ const unsigned long pmd_start_addr = ALIGN_DOWN(addr, PMD_SIZE);
+ const unsigned long pmd_end_addr = pmd_start_addr + PMD_SIZE;
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *mpnt;
unsigned long offset;
@@ -142,6 +142,14 @@ make_coherent(struct address_space *mapp
flush_dcache_mmap_lock(mapping);
vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
/*
+ * If we are using split PTE locks, then we need to take the pte
+ * lock. Otherwise we are using shared mm->page_table_lock which
+ * is already locked, thus cannot take it.
+ */
+ bool need_lock = IS_ENABLED(CONFIG_SPLIT_PTE_PTLOCKS);
+ unsigned long mpnt_addr;
+
+ /*
* If this VMA is not in our MM, we can ignore it.
* Note that we intentionally mask out the VMA
* that we are fixing up.
@@ -151,7 +159,12 @@ make_coherent(struct address_space *mapp
if (!(mpnt->vm_flags & VM_MAYSHARE))
continue;
offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
- aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn, vmf);
+ mpnt_addr = mpnt->vm_start + offset;
+
+ /* Avoid deadlocks by not grabbing the same PTE lock again. */
+ if (mpnt_addr >= pmd_start_addr && mpnt_addr < pmd_end_addr)
+ need_lock = false;
+ aliases += adjust_pte(mpnt, mpnt_addr, pfn, need_lock);
}
flush_dcache_mmap_unlock(mapping);
if (aliases)
@@ -194,7 +207,7 @@ void update_mmu_cache_range(struct vm_fa
__flush_dcache_folio(mapping, folio);
if (mapping) {
if (cache_is_vivt())
- make_coherent(mapping, vma, addr, ptep, pfn, vmf);
+ make_coherent(mapping, vma, addr, ptep, pfn);
else if (vma->vm_flags & VM_EXEC)
__flush_icache_all();
}
_
Patches currently in -mm which might be from zhengqi.arch@bytedance.com are
mm-pgtable-fix-incorrect-reclaim-of-non-empty-pte-pages.patch
arm-pgtable-fix-null-pointer-dereference-issue.patch
^ permalink raw reply [flat|nested] 2+ messages in thread
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