| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <1503007519-26777-3-git-send-email-ldufour@linux.vnet.ibm.com>
Date: Fri, 18 Aug 2017 00:05:01 +0200
From: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To: paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
akpm@...ux-foundation.org, kirill@...temov.name,
ak@...ux.intel.com, mhocko@...nel.org, dave@...olabs.net,
jack@...e.cz, Matthew Wilcox <willy@...radead.org>,
benh@...nel.crashing.org, mpe@...erman.id.au, paulus@...ba.org,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
Will Deacon <will.deacon@....com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
haren@...ux.vnet.ibm.com, khandual@...ux.vnet.ibm.com,
npiggin@...il.com, bsingharora@...il.com,
Tim Chen <tim.c.chen@...ux.intel.com>,
linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: [PATCH v2 02/20] mm: Prepare for FAULT_FLAG_SPECULATIVE
From: Peter Zijlstra <peterz@...radead.org>
When speculating faults (without holding mmap_sem) we need to validate
that the vma against which we loaded pages is still valid when we're
ready to install the new PTE.
Therefore, replace the pte_offset_map_lock() calls that (re)take the
PTL with pte_map_lock() which can fail in case we find the VMA changed
since we started the fault.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
[Port to 4.12 kernel]
[Remove the comment about the fault_env structure which has been
implemented as the vm_fault structure in the kernel]
Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
---
include/linux/mm.h | 1 +
mm/memory.c | 55 ++++++++++++++++++++++++++++++++++++++----------------
2 files changed, 40 insertions(+), 16 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 46b9ac5e8569..8763ec96dc78 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -286,6 +286,7 @@ extern pgprot_t protection_map[16];
#define FAULT_FLAG_USER 0x40 /* The fault originated in userspace */
#define FAULT_FLAG_REMOTE 0x80 /* faulting for non current tsk/mm */
#define FAULT_FLAG_INSTRUCTION 0x100 /* The fault was during an instruction fetch */
+#define FAULT_FLAG_SPECULATIVE 0x200 /* Speculative fault, not holding mmap_sem */
#define FAULT_FLAG_TRACE \
{ FAULT_FLAG_WRITE, "WRITE" }, \
diff --git a/mm/memory.c b/mm/memory.c
index 36609c082256..3ed1b00ca841 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2269,6 +2269,12 @@ static inline void wp_page_reuse(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
}
+static bool pte_map_lock(struct vm_fault *vmf)
+{
+ vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl);
+ return true;
+}
+
/*
* Handle the case of a page which we actually need to copy to a new page.
*
@@ -2296,6 +2302,7 @@ static int wp_page_copy(struct vm_fault *vmf)
const unsigned long mmun_start = vmf->address & PAGE_MASK;
const unsigned long mmun_end = mmun_start + PAGE_SIZE;
struct mem_cgroup *memcg;
+ int ret = VM_FAULT_OOM;
if (unlikely(anon_vma_prepare(vma)))
goto oom;
@@ -2323,7 +2330,11 @@ static int wp_page_copy(struct vm_fault *vmf)
/*
* Re-check the pte - we dropped the lock
*/
- vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
+ if (!pte_map_lock(vmf)) {
+ mem_cgroup_cancel_charge(new_page, memcg, false);
+ ret = VM_FAULT_RETRY;
+ goto oom_free_new;
+ }
if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
if (old_page) {
if (!PageAnon(old_page)) {
@@ -2411,7 +2422,7 @@ static int wp_page_copy(struct vm_fault *vmf)
oom:
if (old_page)
put_page(old_page);
- return VM_FAULT_OOM;
+ return ret;
}
/**
@@ -2432,8 +2443,8 @@ static int wp_page_copy(struct vm_fault *vmf)
int finish_mkwrite_fault(struct vm_fault *vmf)
{
WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
- vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
- &vmf->ptl);
+ if (!pte_map_lock(vmf))
+ return VM_FAULT_RETRY;
/*
* We might have raced with another page fault while we released the
* pte_offset_map_lock.
@@ -2551,8 +2562,11 @@ static int do_wp_page(struct vm_fault *vmf)
get_page(vmf->page);
pte_unmap_unlock(vmf->pte, vmf->ptl);
lock_page(vmf->page);
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
- vmf->address, &vmf->ptl);
+ if (!pte_map_lock(vmf)) {
+ unlock_page(vmf->page);
+ put_page(vmf->page);
+ return VM_FAULT_RETRY;
+ }
if (!pte_same(*vmf->pte, vmf->orig_pte)) {
unlock_page(vmf->page);
pte_unmap_unlock(vmf->pte, vmf->ptl);
@@ -2710,8 +2724,10 @@ int do_swap_page(struct vm_fault *vmf)
* Back out if somebody else faulted in this pte
* while we released the pte lock.
*/
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
- vmf->address, &vmf->ptl);
+ if (!pte_map_lock(vmf)) {
+ delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+ return VM_FAULT_RETRY;
+ }
if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
ret = VM_FAULT_OOM;
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
@@ -2767,8 +2783,11 @@ int do_swap_page(struct vm_fault *vmf)
/*
* Back out if somebody else already faulted in this pte.
*/
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
- &vmf->ptl);
+ if (!pte_map_lock(vmf)) {
+ ret = VM_FAULT_RETRY;
+ mem_cgroup_cancel_charge(page, memcg, false);
+ goto out_page;
+ }
if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
goto out_nomap;
@@ -2894,8 +2913,8 @@ static int do_anonymous_page(struct vm_fault *vmf)
!mm_forbids_zeropage(vma->vm_mm)) {
entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
vma->vm_page_prot));
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
- vmf->address, &vmf->ptl);
+ if (!pte_map_lock(vmf))
+ return VM_FAULT_RETRY;
if (!pte_none(*vmf->pte))
goto unlock;
/* Deliver the page fault to userland, check inside PT lock */
@@ -2927,8 +2946,11 @@ static int do_anonymous_page(struct vm_fault *vmf)
if (vma->vm_flags & VM_WRITE)
entry = pte_mkwrite(pte_mkdirty(entry));
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
- &vmf->ptl);
+ if (!pte_map_lock(vmf)) {
+ mem_cgroup_cancel_charge(page, memcg, false);
+ put_page(page);
+ return VM_FAULT_RETRY;
+ }
if (!pte_none(*vmf->pte))
goto release;
@@ -3048,8 +3070,9 @@ static int pte_alloc_one_map(struct vm_fault *vmf)
* pte_none() under vmf->ptl protection when we return to
* alloc_set_pte().
*/
- vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
- &vmf->ptl);
+ if (!pte_map_lock(vmf))
+ return VM_FAULT_RETRY;
+
return 0;
}
--
2.7.4
Powered by blists - more mailing lists