The patch titled
Subject: mm/hugetlb: fix PTE marker handling in hugetlb_change_protection()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-hugetlb-fix-pte-marker-handling-in-hugetlb_change_protection.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david(a)redhat.com>
Subject: mm/hugetlb: fix PTE marker handling in hugetlb_change_protection()
Date: Thu, 22 Dec 2022 21:55:10 +0100
Patch series "mm/hugetlb: uffd-wp fixes for hugetlb_change_protection()".
Playing with virtio-mem and background snapshots (using uffd-wp) on
hugetlb in QEMU, I managed to trigger a VM_BUG_ON(). Looking into the
details, hugetlb_change_protection() seems to not handle uffd-wp correctly
in all cases.
Patch #1 fixes my test case. I don't have reproducers for patch #2, as it
requires running into migration entries.
I did not yet check in detail yet if !hugetlb code requires similar care.
This patch (of 2):
There are two problematic cases when stumbling over a PTE marker in
hugetlb_change_protection():
(1) We protect an uffd-wp PTE marker a second time using uffd-wp: we will
end up in the "!huge_pte_none(pte)" case and mess up the PTE marker.
(2) We unprotect a uffd-wp PTE marker: we will similarly end up in the
"!huge_pte_none(pte)" case even though we cleared the PTE, because
the "pte" variable is stale. We'll mess up the PTE marker.
For example, if we later stumble over such a "wrongly modified" PTE marker,
we'll treat it like a present PTE that maps some garbage page.
This can, for example, be triggered by mapping a memfd backed by huge
pages, registering uffd-wp, uffd-wp'ing an unmapped page and (a)
uffd-wp'ing it a second time; or (b) uffd-unprotecting it; or (c)
unregistering uffd-wp. Then, ff we trigger fallocate(FALLOC_FL_PUNCH_HOLE)
on that file range, we will run into a VM_BUG_ON:
[ 195.039560] page:00000000ba1f2987 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x0
[ 195.039565] flags: 0x7ffffc0001000(reserved|node=0|zone=0|lastcpupid=0x1fffff)
[ 195.039568] raw: 0007ffffc0001000 ffffe742c0000008 ffffe742c0000008 0000000000000000
[ 195.039569] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
[ 195.039569] page dumped because: VM_BUG_ON_PAGE(compound && !PageHead(page))
[ 195.039573] ------------[ cut here ]------------
[ 195.039574] kernel BUG at mm/rmap.c:1346!
[ 195.039579] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 195.039581] CPU: 7 PID: 4777 Comm: qemu-system-x86 Not tainted 6.0.12-200.fc36.x86_64 #1
[ 195.039583] Hardware name: LENOVO 20WNS1F81N/20WNS1F81N, BIOS N35ET50W (1.50 ) 09/15/2022
[ 195.039584] RIP: 0010:page_remove_rmap+0x45b/0x550
[ 195.039588] Code: [...]
[ 195.039589] RSP: 0018:ffffbc03c3633ba8 EFLAGS: 00010292
[ 195.039591] RAX: 0000000000000040 RBX: ffffe742c0000000 RCX: 0000000000000000
[ 195.039592] RDX: 0000000000000002 RSI: ffffffff8e7aac1a RDI: 00000000ffffffff
[ 195.039592] RBP: 0000000000000001 R08: 0000000000000000 R09: ffffbc03c3633a08
[ 195.039593] R10: 0000000000000003 R11: ffffffff8f146328 R12: ffff9b04c42754b0
[ 195.039594] R13: ffffffff8fcc6328 R14: ffffbc03c3633c80 R15: ffff9b0484ab9100
[ 195.039595] FS: 00007fc7aaf68640(0000) GS:ffff9b0bbf7c0000(0000) knlGS:0000000000000000
[ 195.039596] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 195.039597] CR2: 000055d402c49110 CR3: 0000000159392003 CR4: 0000000000772ee0
[ 195.039598] PKRU: 55555554
[ 195.039599] Call Trace:
[ 195.039600] <TASK>
[ 195.039602] __unmap_hugepage_range+0x33b/0x7d0
[ 195.039605] unmap_hugepage_range+0x55/0x70
[ 195.039608] hugetlb_vmdelete_list+0x77/0xa0
[ 195.039611] hugetlbfs_fallocate+0x410/0x550
[ 195.039612] ? _raw_spin_unlock_irqrestore+0x23/0x40
[ 195.039616] vfs_fallocate+0x12e/0x360
[ 195.039618] __x64_sys_fallocate+0x40/0x70
[ 195.039620] do_syscall_64+0x58/0x80
[ 195.039623] ? syscall_exit_to_user_mode+0x17/0x40
[ 195.039624] ? do_syscall_64+0x67/0x80
[ 195.039626] entry_SYSCALL_64_after_hwframe+0x63/0xcd
[ 195.039628] RIP: 0033:0x7fc7b590651f
[ 195.039653] Code: [...]
[ 195.039654] RSP: 002b:00007fc7aaf66e70 EFLAGS: 00000293 ORIG_RAX: 000000000000011d
[ 195.039655] RAX: ffffffffffffffda RBX: 0000558ef4b7f370 RCX: 00007fc7b590651f
[ 195.039656] RDX: 0000000018000000 RSI: 0000000000000003 RDI: 000000000000000c
[ 195.039657] RBP: 0000000008000000 R08: 0000000000000000 R09: 0000000000000073
[ 195.039658] R10: 0000000008000000 R11: 0000000000000293 R12: 0000000018000000
[ 195.039658] R13: 00007fb8bbe00000 R14: 000000000000000c R15: 0000000000001000
[ 195.039661] </TASK>
Fix it by not going into the "!huge_pte_none(pte)" case if we stumble over
an exclusive marker. spin_unlock() + continue would get the job done.
However, instead, make it clearer that there are no fall-through
statements: we process each case (hwpoison, migration, marker, !none,
none) and then unlock the page table to continue with the next PTE. Let's
avoid "continue" statements and use a single spin_unlock() at the end.
Link: https://lkml.kernel.org/r/20221222205511.675832-1-david@redhat.com
Link: https://lkml.kernel.org/r/20221222205511.675832-2-david@redhat.com
Fixes: 60dfaad65aa9 ("mm/hugetlb: allow uffd wr-protect none ptes")
Signed-off-by: David Hildenbrand <david(a)redhat.com>
Cc: Miaohe Lin <linmiaohe(a)huawei.com>
Cc: Mike Kravetz <mike.kravetz(a)oracle.com>
Cc: Muchun Song <muchun.song(a)linux.dev>
Cc: Peter Xu <peterx(a)redhat.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
--- a/mm/hugetlb.c~mm-hugetlb-fix-pte-marker-handling-in-hugetlb_change_protection
+++ a/mm/hugetlb.c
@@ -6658,10 +6658,8 @@ unsigned long hugetlb_change_protection(
}
pte = huge_ptep_get(ptep);
if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
- spin_unlock(ptl);
- continue;
- }
- if (unlikely(is_hugetlb_entry_migration(pte))) {
+ /* Nothing to do. */
+ } else if (unlikely(is_hugetlb_entry_migration(pte))) {
swp_entry_t entry = pte_to_swp_entry(pte);
struct page *page = pfn_swap_entry_to_page(entry);
@@ -6682,18 +6680,13 @@ unsigned long hugetlb_change_protection(
set_huge_pte_at(mm, address, ptep, newpte);
pages++;
}
- spin_unlock(ptl);
- continue;
- }
- if (unlikely(pte_marker_uffd_wp(pte))) {
- /*
- * This is changing a non-present pte into a none pte,
- * no need for huge_ptep_modify_prot_start/commit().
- */
+ } else if (unlikely(is_pte_marker(pte))) {
+ /* No other markers apply for now. */
+ WARN_ON_ONCE(!pte_marker_uffd_wp(pte));
if (uffd_wp_resolve)
+ /* Safe to modify directly (non-present->none). */
huge_pte_clear(mm, address, ptep, psize);
- }
- if (!huge_pte_none(pte)) {
+ } else if (!huge_pte_none(pte)) {
pte_t old_pte;
unsigned int shift = huge_page_shift(hstate_vma(vma));
_
Patches currently in -mm which might be from david(a)redhat.com are
mm-hugetlb-fix-pte-marker-handling-in-hugetlb_change_protection.patch
mm-hugetlb-fix-uffd-wp-handling-for-migration-entries-in-hugetlb_change_protection.patch
Since commit 07ec77a1d4e8 ("sched: Allow task CPU affinity to be
restricted on asymmetric systems"), the setting and clearing of
user_cpus_ptr are done under pi_lock for arm64 architecture. However,
dup_user_cpus_ptr() accesses user_cpus_ptr without any lock
protection. When racing with the clearing of user_cpus_ptr in
__set_cpus_allowed_ptr_locked(), it can lead to user-after-free and
double-free in arm64 kernel.
Commit 8f9ea86fdf99 ("sched: Always preserve the user requested
cpumask") fixes this problem as user_cpus_ptr, once set, will never
be cleared in a task's lifetime. However, this bug was re-introduced
in commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in
do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in
do_set_cpus_allowed(). This time, it will affect all arches.
Fix this bug by always clearing the user_cpus_ptr of the newly
cloned/forked task before the copying process starts and check the
user_cpus_ptr state of the source task under pi_lock.
Note to stable, this patch won't be applicable to stable releases.
Just copy the new dup_user_cpus_ptr() function over.
Fixes: 07ec77a1d4e8 ("sched: Allow task CPU affinity to be restricted on asymmetric systems")
Fixes: 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()")
CC: stable(a)vger.kernel.org
Reported-by: David Wang 王标 <wangbiao3(a)xiaomi.com>
Signed-off-by: Waiman Long <longman(a)redhat.com>
---
kernel/sched/core.c | 34 +++++++++++++++++++++++++++++-----
1 file changed, 29 insertions(+), 5 deletions(-)
[v2: Use data_race() macro as suggested by Will]
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 78b2d5cabcc5..57e5932f81a9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2612,19 +2612,43 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src,
int node)
{
+ cpumask_t *user_mask;
unsigned long flags;
- if (!src->user_cpus_ptr)
+ /*
+ * Always clear dst->user_cpus_ptr first as their user_cpus_ptr's
+ * may differ by now due to racing.
+ */
+ dst->user_cpus_ptr = NULL;
+
+ /*
+ * This check is racy and losing the race is a valid situation.
+ * It is not worth the extra overhead of taking the pi_lock on
+ * every fork/clone.
+ */
+ if (data_race(!src->user_cpus_ptr))
return 0;
- dst->user_cpus_ptr = kmalloc_node(cpumask_size(), GFP_KERNEL, node);
- if (!dst->user_cpus_ptr)
+ user_mask = kmalloc_node(cpumask_size(), GFP_KERNEL, node);
+ if (!user_mask)
return -ENOMEM;
- /* Use pi_lock to protect content of user_cpus_ptr */
+ /*
+ * Use pi_lock to protect content of user_cpus_ptr
+ *
+ * Though unlikely, user_cpus_ptr can be reset to NULL by a concurrent
+ * do_set_cpus_allowed().
+ */
raw_spin_lock_irqsave(&src->pi_lock, flags);
- cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr);
+ if (src->user_cpus_ptr) {
+ swap(dst->user_cpus_ptr, user_mask);
+ cpumask_copy(dst->user_cpus_ptr, src->user_cpus_ptr);
+ }
raw_spin_unlock_irqrestore(&src->pi_lock, flags);
+
+ if (unlikely(user_mask))
+ kfree(user_mask);
+
return 0;
}
--
2.31.1
Hi,
It was reported that on 5.15.y there are problems with S3 suspend root
caused to a W6400 problem. [1]
These are fixed by this commit:
a9a1ac44074f ("drm/amd/display: Manually adjust strobe for DCN303")
Can you please bring it to 5.15.y?
Thanks,
[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2000299
The memory for "llcc_driv_data" is allocated by the LLCC driver. But when
it is passed as "pvt_info" to the EDAC core, it will get freed during the
qcom_edac driver release. So when the qcom_edac driver gets probed again,
it will try to use the freed data leading to the use-after-free bug.
Fix this by not passing "llcc_driv_data" as pvt_info but rather reference
it using the "platform_data" in the qcom_edac driver.
Cc: <stable(a)vger.kernel.org> # 4.20
Fixes: 27450653f1db ("drivers: edac: Add EDAC driver support for QCOM SoCs")
Reported-by: Steev Klimaszewski <steev(a)kali.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam(a)linaro.org>
---
drivers/edac/qcom_edac.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/edac/qcom_edac.c b/drivers/edac/qcom_edac.c
index 9e77fa84e84f..3256254c3722 100644
--- a/drivers/edac/qcom_edac.c
+++ b/drivers/edac/qcom_edac.c
@@ -252,7 +252,7 @@ dump_syn_reg_values(struct llcc_drv_data *drv, u32 bank, int err_type)
static int
dump_syn_reg(struct edac_device_ctl_info *edev_ctl, int err_type, u32 bank)
{
- struct llcc_drv_data *drv = edev_ctl->pvt_info;
+ struct llcc_drv_data *drv = edev_ctl->dev->platform_data;
int ret;
ret = dump_syn_reg_values(drv, bank, err_type);
@@ -289,7 +289,7 @@ static irqreturn_t
llcc_ecc_irq_handler(int irq, void *edev_ctl)
{
struct edac_device_ctl_info *edac_dev_ctl = edev_ctl;
- struct llcc_drv_data *drv = edac_dev_ctl->pvt_info;
+ struct llcc_drv_data *drv = edac_dev_ctl->dev->platform_data;
irqreturn_t irq_rc = IRQ_NONE;
u32 drp_error, trp_error, i;
int ret;
@@ -358,7 +358,6 @@ static int qcom_llcc_edac_probe(struct platform_device *pdev)
edev_ctl->dev_name = dev_name(dev);
edev_ctl->ctl_name = "llcc";
edev_ctl->panic_on_ue = LLCC_ERP_PANIC_ON_UE;
- edev_ctl->pvt_info = llcc_driv_data;
rc = edac_device_add_device(edev_ctl);
if (rc)
--
2.25.1