On Sat, Nov 24, 2018 at 11:54 PM Sasha Levin <sashal(a)kernel.org> wrote:
>
> Hi,
>
> [This is an automated email]
>
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: cfe30b872058 libnvdimm, pmem: adjust for section collisions with 'System RAM'.
>
> The bot has tested the following trees: v4.19.4, v4.14.83, v4.9.140.
>
> v4.19.4: Build OK!
> v4.14.83: Build OK!
> v4.9.140: Failed to apply! Possible dependencies:
> Unable to calculate
>
>
> How should we proceed with this patch?
4.9-stable will need a manual backport since this code was refactored
in the intervening kernel releases.
The patch titled
Subject: lib/test_kmod.c: fix rmmod double free
has been added to the -mm tree. Its filename is
test_kmod-fix-rmmod-double-free.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/test_kmod-fix-rmmod-double-free.pa…
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/test_kmod-fix-rmmod-double-free.pa…
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 and is updated
there every 3-4 working days
------------------------------------------------------
From: Luis Chamberlain <mcgrof(a)kernel.org>
Subject: lib/test_kmod.c: fix rmmod double free
We free the misc device string twice on rmmod; fix this. Without this we
cannot remove the module without crashing.
Link: http://lkml.kernel.org/r/20181124050500.5257-1-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain <mcgrof(a)kernel.org>
Reported-by: Randy Dunlap <rdunlap(a)infradead.org>
Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org>
Cc: <stable(a)vger.kernel.org> [4.12+]
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
--- a/lib/test_kmod.c~test_kmod-fix-rmmod-double-free
+++ a/lib/test_kmod.c
@@ -1214,7 +1214,6 @@ void unregister_test_dev_kmod(struct kmo
dev_info(test_dev->dev, "removing interface\n");
misc_deregister(&test_dev->misc_dev);
- kfree(&test_dev->misc_dev.name);
mutex_unlock(&test_dev->config_mutex);
mutex_unlock(&test_dev->trigger_mutex);
_
Patches currently in -mm which might be from mcgrof(a)kernel.org are
maintainers-update-name-change-for-myself.patch
test_kmod-fix-rmmod-double-free.patch
The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From b082f2dd80612015cd6d9d84e52099734ec9a0e1 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov(a)linux.intel.com>
Date: Fri, 26 Oct 2018 15:28:56 +0300
Subject: [PATCH] x86/ldt: Remove unused variable in map_ldt_struct()
Splitting out the sanity check in map_ldt_struct() moved page table syncing
into a separate function, which made the pgd variable unused. Remove it.
[ tglx: Massaged changelog ]
Fixes: 9bae3197e15d ("x86/ldt: Split out sanity check in map_ldt_struct()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Reviewed-by: Andy Lutomirski <luto(a)kernel.org>
Cc: bp(a)alien8.de
Cc: hpa(a)zytor.com
Cc: dave.hansen(a)linux.intel.com
Cc: peterz(a)infradead.org
Cc: boris.ostrovsky(a)oracle.com
Cc: jgross(a)suse.com
Cc: bhe(a)redhat.com
Cc: willy(a)infradead.org
Cc: linux-mm(a)kvack.org
Cc: stable(a)vger.kernel.org
Link: https://lkml.kernel.org/r/20181026122856.66224-4-kirill.shutemov@linux.inte…
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 18e4525c5933..6135ae8ce036 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -207,7 +207,6 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
bool is_vmalloc;
spinlock_t *ptl;
int i, nr_pages;
- pgd_t *pgd;
if (!static_cpu_has(X86_FEATURE_PTI))
return 0;
@@ -221,13 +220,6 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
/* Check if the current mappings are sane */
sanity_check_ldt_mapping(mm);
- /*
- * Did we already have the top level entry allocated? We can't
- * use pgd_none() for this because it doens't do anything on
- * 4-level page table kernels.
- */
- pgd = pgd_offset(mm, LDT_BASE_ADDR);
-
is_vmalloc = is_vmalloc_addr(ldt->entries);
nr_pages = DIV_ROUND_UP(ldt->nr_entries * LDT_ENTRY_SIZE, PAGE_SIZE);
The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From a0e6e0831c516860fc7f9be1db6c081fe902ebcf Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov(a)linux.intel.com>
Date: Fri, 26 Oct 2018 15:28:55 +0300
Subject: [PATCH] x86/ldt: Unmap PTEs for the slot before freeing LDT pages
modify_ldt(2) leaves the old LDT mapped after switching over to the new
one. The old LDT gets freed and the pages can be re-used.
Leaving the mapping in place can have security implications. The mapping is
present in the userspace page tables and Meltdown-like attacks can read
these freed and possibly reused pages.
It's relatively simple to fix: unmap the old LDT and flush TLB before
freeing the old LDT memory.
This further allows to avoid flushing the TLB in map_ldt_struct() as the
slot is unmapped and flushed by unmap_ldt_struct() or has never been mapped
at all.
[ tglx: Massaged changelog and removed the needless line breaks ]
Fixes: f55f0501cbf6 ("x86/pti: Put the LDT in its own PGD if PTI is on")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de>
Cc: bp(a)alien8.de
Cc: hpa(a)zytor.com
Cc: dave.hansen(a)linux.intel.com
Cc: luto(a)kernel.org
Cc: peterz(a)infradead.org
Cc: boris.ostrovsky(a)oracle.com
Cc: jgross(a)suse.com
Cc: bhe(a)redhat.com
Cc: willy(a)infradead.org
Cc: linux-mm(a)kvack.org
Cc: stable(a)vger.kernel.org
Link: https://lkml.kernel.org/r/20181026122856.66224-3-kirill.shutemov@linux.inte…
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index ab18e0884dc6..18e4525c5933 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -199,14 +199,6 @@ static void sanity_check_ldt_mapping(struct mm_struct *mm)
/*
* If PTI is enabled, this maps the LDT into the kernelmode and
* usermode tables for the given mm.
- *
- * There is no corresponding unmap function. Even if the LDT is freed, we
- * leave the PTEs around until the slot is reused or the mm is destroyed.
- * This is harmless: the LDT is always in ordinary memory, and no one will
- * access the freed slot.
- *
- * If we wanted to unmap freed LDTs, we'd also need to do a flush to make
- * it useful, and the flush would slow down modify_ldt().
*/
static int
map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
@@ -214,8 +206,8 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
unsigned long va;
bool is_vmalloc;
spinlock_t *ptl;
+ int i, nr_pages;
pgd_t *pgd;
- int i;
if (!static_cpu_has(X86_FEATURE_PTI))
return 0;
@@ -238,7 +230,9 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
is_vmalloc = is_vmalloc_addr(ldt->entries);
- for (i = 0; i * PAGE_SIZE < ldt->nr_entries * LDT_ENTRY_SIZE; i++) {
+ nr_pages = DIV_ROUND_UP(ldt->nr_entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+
+ for (i = 0; i < nr_pages; i++) {
unsigned long offset = i << PAGE_SHIFT;
const void *src = (char *)ldt->entries + offset;
unsigned long pfn;
@@ -272,13 +266,39 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
/* Propagate LDT mapping to the user page-table */
map_ldt_struct_to_user(mm);
- va = (unsigned long)ldt_slot_va(slot);
- flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, PAGE_SHIFT, false);
-
ldt->slot = slot;
return 0;
}
+static void unmap_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt)
+{
+ unsigned long va;
+ int i, nr_pages;
+
+ if (!ldt)
+ return;
+
+ /* LDT map/unmap is only required for PTI */
+ if (!static_cpu_has(X86_FEATURE_PTI))
+ return;
+
+ nr_pages = DIV_ROUND_UP(ldt->nr_entries * LDT_ENTRY_SIZE, PAGE_SIZE);
+
+ for (i = 0; i < nr_pages; i++) {
+ unsigned long offset = i << PAGE_SHIFT;
+ spinlock_t *ptl;
+ pte_t *ptep;
+
+ va = (unsigned long)ldt_slot_va(ldt->slot) + offset;
+ ptep = get_locked_pte(mm, va, &ptl);
+ pte_clear(mm, va, ptep);
+ pte_unmap_unlock(ptep, ptl);
+ }
+
+ va = (unsigned long)ldt_slot_va(ldt->slot);
+ flush_tlb_mm_range(mm, va, va + nr_pages * PAGE_SIZE, PAGE_SHIFT, false);
+}
+
#else /* !CONFIG_PAGE_TABLE_ISOLATION */
static int
@@ -286,6 +306,10 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
{
return 0;
}
+
+static void unmap_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt)
+{
+}
#endif /* CONFIG_PAGE_TABLE_ISOLATION */
static void free_ldt_pgtables(struct mm_struct *mm)
@@ -524,6 +548,7 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
}
install_ldt(mm, new_ldt);
+ unmap_ldt_struct(mm, old_ldt);
free_ldt_struct(old_ldt);
error = 0;