From: Todd Kjos <tkjos(a)android.com>
commit 7bada55ab50697861eee6bb7d60b41e68a961a9c upstream
Malicious code can attempt to free buffers using the BC_FREE_BUFFER
ioctl to binder. There are protections against a user freeing a buffer
while in use by the kernel, however there was a window where
BC_FREE_BUFFER could be used to free a recently allocated buffer that
was not completely initialized. This resulted in a use-after-free
detected by KASAN with a malicious test program.
This window is closed by setting the buffer's allow_user_free attribute
to 0 when the buffer is allocated or when the user has previously freed
it instead of waiting for the caller to set it. The problem was that
when the struct buffer was recycled, allow_user_free was stale and set
to 1 allowing a free to go through.
Signed-off-by: Todd Kjos <tkjos(a)google.com>
Acked-by: Arve Hjønnevåg <arve(a)android.com>
Cc: stable <stable(a)vger.kernel.org> # 4.14
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/android/binder.c | 21 ++++++++++++---------
drivers/android/binder_alloc.c | 14 ++++++--------
drivers/android/binder_alloc.h | 3 +--
3 files changed, 19 insertions(+), 19 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index a86c27948fcab..96a0f940e54d9 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2918,7 +2918,6 @@ static void binder_transaction(struct binder_proc *proc,
t->buffer = NULL;
goto err_binder_alloc_buf_failed;
}
- t->buffer->allow_user_free = 0;
t->buffer->debug_id = t->debug_id;
t->buffer->transaction = t;
t->buffer->target_node = target_node;
@@ -3407,14 +3406,18 @@ static int binder_thread_write(struct binder_proc *proc,
buffer = binder_alloc_prepare_to_free(&proc->alloc,
data_ptr);
- if (buffer == NULL) {
- binder_user_error("%d:%d BC_FREE_BUFFER u%016llx no match\n",
- proc->pid, thread->pid, (u64)data_ptr);
- break;
- }
- if (!buffer->allow_user_free) {
- binder_user_error("%d:%d BC_FREE_BUFFER u%016llx matched unreturned buffer\n",
- proc->pid, thread->pid, (u64)data_ptr);
+ if (IS_ERR_OR_NULL(buffer)) {
+ if (PTR_ERR(buffer) == -EPERM) {
+ binder_user_error(
+ "%d:%d BC_FREE_BUFFER u%016llx matched unreturned or currently freeing buffer\n",
+ proc->pid, thread->pid,
+ (u64)data_ptr);
+ } else {
+ binder_user_error(
+ "%d:%d BC_FREE_BUFFER u%016llx no match\n",
+ proc->pid, thread->pid,
+ (u64)data_ptr);
+ }
break;
}
binder_debug(BINDER_DEBUG_FREE_BUFFER,
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 58e4658f9dd6c..b9281f2725a6a 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -149,14 +149,12 @@ static struct binder_buffer *binder_alloc_prepare_to_free_locked(
else {
/*
* Guard against user threads attempting to
- * free the buffer twice
+ * free the buffer when in use by kernel or
+ * after it's already been freed.
*/
- if (buffer->free_in_progress) {
- pr_err("%d:%d FREE_BUFFER u%016llx user freed buffer twice\n",
- alloc->pid, current->pid, (u64)user_ptr);
- return NULL;
- }
- buffer->free_in_progress = 1;
+ if (!buffer->allow_user_free)
+ return ERR_PTR(-EPERM);
+ buffer->allow_user_free = 0;
return buffer;
}
}
@@ -486,7 +484,7 @@ struct binder_buffer *binder_alloc_new_buf_locked(struct binder_alloc *alloc,
rb_erase(best_fit, &alloc->free_buffers);
buffer->free = 0;
- buffer->free_in_progress = 0;
+ buffer->allow_user_free = 0;
binder_insert_allocated_buffer_locked(alloc, buffer);
binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
"%d: binder_alloc_buf size %zd got %pK\n",
diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index 2dd33b6df1044..a3ad7683b6f23 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -50,8 +50,7 @@ struct binder_buffer {
unsigned free:1;
unsigned allow_user_free:1;
unsigned async_transaction:1;
- unsigned free_in_progress:1;
- unsigned debug_id:28;
+ unsigned debug_id:29;
struct binder_transaction *transaction;
--
2.20.0.rc1.387.gf8505762e3-goog
The patch below does not apply to the 3.18-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 6ff38bd40230af35e446239396e5fc8ebd6a5248 Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Date: Fri, 30 Nov 2018 14:09:00 -0800
Subject: [PATCH] mm: cleancache: fix corruption on missed inode invalidation
If all pages are deleted from the mapping by memory reclaim and also
moved to the cleancache:
__delete_from_page_cache
(no shadow case)
unaccount_page_cache_page
cleancache_put_page
page_cache_delete
mapping->nrpages -= nr
(nrpages becomes 0)
We don't clean the cleancache for an inode after final file truncation
(removal).
truncate_inode_pages_final
check (nrpages || nrexceptional) is false
no truncate_inode_pages
no cleancache_invalidate_inode(mapping)
These way when reading the new file created with same inode we may get
these trash leftover pages from cleancache and see wrong data instead of
the contents of the new file.
Fix it by always doing truncate_inode_pages which is already ready for
nrpages == 0 && nrexceptional == 0 case and just invalidates inode.
[akpm(a)linux-foundation.org: add comment, per Jan]
Link: http://lkml.kernel.org/r/20181112095734.17979-1-ptikhomirov@virtuozzo.com
Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache")
Signed-off-by: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Reviewed-by: Vasily Averin <vvs(a)virtuozzo.com>
Reviewed-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
diff --git a/mm/truncate.c b/mm/truncate.c
index 45d68e90b703..798e7ccfb030 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -517,9 +517,13 @@ void truncate_inode_pages_final(struct address_space *mapping)
*/
xa_lock_irq(&mapping->i_pages);
xa_unlock_irq(&mapping->i_pages);
-
- truncate_inode_pages(mapping, 0);
}
+
+ /*
+ * Cleancache needs notification even if there are no pages or shadow
+ * entries.
+ */
+ truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(truncate_inode_pages_final);
The patch below does not apply to the 4.4-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 6ff38bd40230af35e446239396e5fc8ebd6a5248 Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Date: Fri, 30 Nov 2018 14:09:00 -0800
Subject: [PATCH] mm: cleancache: fix corruption on missed inode invalidation
If all pages are deleted from the mapping by memory reclaim and also
moved to the cleancache:
__delete_from_page_cache
(no shadow case)
unaccount_page_cache_page
cleancache_put_page
page_cache_delete
mapping->nrpages -= nr
(nrpages becomes 0)
We don't clean the cleancache for an inode after final file truncation
(removal).
truncate_inode_pages_final
check (nrpages || nrexceptional) is false
no truncate_inode_pages
no cleancache_invalidate_inode(mapping)
These way when reading the new file created with same inode we may get
these trash leftover pages from cleancache and see wrong data instead of
the contents of the new file.
Fix it by always doing truncate_inode_pages which is already ready for
nrpages == 0 && nrexceptional == 0 case and just invalidates inode.
[akpm(a)linux-foundation.org: add comment, per Jan]
Link: http://lkml.kernel.org/r/20181112095734.17979-1-ptikhomirov@virtuozzo.com
Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache")
Signed-off-by: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Reviewed-by: Vasily Averin <vvs(a)virtuozzo.com>
Reviewed-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
diff --git a/mm/truncate.c b/mm/truncate.c
index 45d68e90b703..798e7ccfb030 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -517,9 +517,13 @@ void truncate_inode_pages_final(struct address_space *mapping)
*/
xa_lock_irq(&mapping->i_pages);
xa_unlock_irq(&mapping->i_pages);
-
- truncate_inode_pages(mapping, 0);
}
+
+ /*
+ * Cleancache needs notification even if there are no pages or shadow
+ * entries.
+ */
+ truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(truncate_inode_pages_final);
The patch below does not apply to the 4.9-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 6ff38bd40230af35e446239396e5fc8ebd6a5248 Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Date: Fri, 30 Nov 2018 14:09:00 -0800
Subject: [PATCH] mm: cleancache: fix corruption on missed inode invalidation
If all pages are deleted from the mapping by memory reclaim and also
moved to the cleancache:
__delete_from_page_cache
(no shadow case)
unaccount_page_cache_page
cleancache_put_page
page_cache_delete
mapping->nrpages -= nr
(nrpages becomes 0)
We don't clean the cleancache for an inode after final file truncation
(removal).
truncate_inode_pages_final
check (nrpages || nrexceptional) is false
no truncate_inode_pages
no cleancache_invalidate_inode(mapping)
These way when reading the new file created with same inode we may get
these trash leftover pages from cleancache and see wrong data instead of
the contents of the new file.
Fix it by always doing truncate_inode_pages which is already ready for
nrpages == 0 && nrexceptional == 0 case and just invalidates inode.
[akpm(a)linux-foundation.org: add comment, per Jan]
Link: http://lkml.kernel.org/r/20181112095734.17979-1-ptikhomirov@virtuozzo.com
Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache")
Signed-off-by: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Reviewed-by: Vasily Averin <vvs(a)virtuozzo.com>
Reviewed-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
diff --git a/mm/truncate.c b/mm/truncate.c
index 45d68e90b703..798e7ccfb030 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -517,9 +517,13 @@ void truncate_inode_pages_final(struct address_space *mapping)
*/
xa_lock_irq(&mapping->i_pages);
xa_unlock_irq(&mapping->i_pages);
-
- truncate_inode_pages(mapping, 0);
}
+
+ /*
+ * Cleancache needs notification even if there are no pages or shadow
+ * entries.
+ */
+ truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(truncate_inode_pages_final);
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 6ff38bd40230af35e446239396e5fc8ebd6a5248 Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Date: Fri, 30 Nov 2018 14:09:00 -0800
Subject: [PATCH] mm: cleancache: fix corruption on missed inode invalidation
If all pages are deleted from the mapping by memory reclaim and also
moved to the cleancache:
__delete_from_page_cache
(no shadow case)
unaccount_page_cache_page
cleancache_put_page
page_cache_delete
mapping->nrpages -= nr
(nrpages becomes 0)
We don't clean the cleancache for an inode after final file truncation
(removal).
truncate_inode_pages_final
check (nrpages || nrexceptional) is false
no truncate_inode_pages
no cleancache_invalidate_inode(mapping)
These way when reading the new file created with same inode we may get
these trash leftover pages from cleancache and see wrong data instead of
the contents of the new file.
Fix it by always doing truncate_inode_pages which is already ready for
nrpages == 0 && nrexceptional == 0 case and just invalidates inode.
[akpm(a)linux-foundation.org: add comment, per Jan]
Link: http://lkml.kernel.org/r/20181112095734.17979-1-ptikhomirov@virtuozzo.com
Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache")
Signed-off-by: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com>
Reviewed-by: Vasily Averin <vvs(a)virtuozzo.com>
Reviewed-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Andi Kleen <ak(a)linux.intel.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
diff --git a/mm/truncate.c b/mm/truncate.c
index 45d68e90b703..798e7ccfb030 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -517,9 +517,13 @@ void truncate_inode_pages_final(struct address_space *mapping)
*/
xa_lock_irq(&mapping->i_pages);
xa_unlock_irq(&mapping->i_pages);
-
- truncate_inode_pages(mapping, 0);
}
+
+ /*
+ * Cleancache needs notification even if there are no pages or shadow
+ * entries.
+ */
+ truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(truncate_inode_pages_final);
Changes since v1 [1]:
* Introduce _safe versions of the set_pte family of helpers (Dave)
* Fix the validation check to accept rewriting the same entry (Peter)
* Fix up the email reference links in the changelogs (Peter)
[1]: https://lkml.org/lkml/2018/11/20/300
---
>From patch 5:
Commit f77084d96355 "x86/mm/pat: Disable preemption around
__flush_tlb_all()" addressed a case where __flush_tlb_all() is called
without preemption being disabled. It also left a warning to catch other
cases where preemption is not disabled. That warning triggers for the
memory hotplug path which is also used for persistent memory enabling:
WARNING: CPU: 35 PID: 911 at ./arch/x86/include/asm/tlbflush.h:460
RIP: 0010:__flush_tlb_all+0x1b/0x3a
[..]
Call Trace:
phys_pud_init+0x29c/0x2bb
kernel_physical_mapping_init+0xfc/0x219
init_memory_mapping+0x1a5/0x3b0
arch_add_memory+0x2c/0x50
devm_memremap_pages+0x3aa/0x610
pmem_attach_disk+0x585/0x700 [nd_pmem]
Andy wondered why a path that can sleep was using __flush_tlb_all() [1]
and Dave confirmed the expectation for TLB flush is for modifying /
invalidating existing pte entries, but not initial population [2]. Drop
the usage of __flush_tlb_all() in phys_{p4d,pud,pmd}_init() on the
expectation that this path is only ever populating empty entries for the
linear map. Note, at linear map teardown time there is a call to the
all-cpu flush_tlb_all() to invalidate the removed mappings.
Additionally, Dave wanted some runtime assurances that
kernel_physical_mapping_init() is only populating and not changing
existing page table entries. Patches 1 - 4 are implementing a new
set_pte() family of helpers for that purpose.
Patch 5 is tagged for -stable because the false positive warning is now
showing up on 4.19-stable kernels. Patches 1 - 4 are not tagged for
-stable, but if the sanity checking is needed please mark them as such.
The hang that was observed while developing the sanity checking
implementation was resolved by Peter's suggestion to not trigger when
the same pte value is being rewritten.
---
Dan Williams (5):
generic/pgtable: Make {pmd,pud}_same() unconditionally available
generic/pgtable: Introduce {p4d,pgd}_same()
generic/pgtable: Introduce set_pte_safe()
x86/mm: Validate kernel_physical_mapping_init() pte population
x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
arch/x86/include/asm/pgalloc.h | 27 +++++++++++++++
arch/x86/mm/init_64.c | 30 +++++++----------
include/asm-generic/5level-fixup.h | 1 +
include/asm-generic/pgtable-nop4d-hack.h | 1 +
include/asm-generic/pgtable-nop4d.h | 1 +
include/asm-generic/pgtable-nopud.h | 1 +
include/asm-generic/pgtable.h | 53 +++++++++++++++++++++++++-----
7 files changed, 87 insertions(+), 27 deletions(-)