From f1181047ff29d4d4d364435040bd347eb54483ca Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Wed, 2 Aug 2017 13:31:52 -0700 Subject: mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries commit 3ea277194daaeaa84ce75180ec7c7a2075027a68 upstream. Stable note for 4.4: The upstream patch patches madvise(MADV_FREE) but 4.4 does not have support for that feature. The changelog is left as-is but the hunk related to madvise is omitted from the backport. Nadav Amit identified a theoritical race between page reclaim and mprotect due to TLB flushes being batched outside of the PTL being held. He described the race as follows: CPU0 CPU1 ---- ---- user accesses memory using RW PTE [PTE now cached in TLB] try_to_unmap_one() ==> ptep_get_and_clear() ==> set_tlb_ubc_flush_pending() mprotect(addr, PROT_READ) ==> change_pte_range() ==> [ PTE non-present - no flush ] user writes using cached RW PTE ... try_to_unmap_flush() The same type of race exists for reads when protecting for PROT_NONE and also exists for operations that can leave an old TLB entry behind such as munmap, mremap and madvise. For some operations like mprotect, it's not necessarily a data integrity issue but it is a correctness issue as there is a window where an mprotect that limits access still allows access. For munmap, it's potentially a data integrity issue although the race is massive as an munmap, mmap and return to userspace must all complete between the window when reclaim drops the PTL and flushes the TLB. However, it's theoritically possible so handle this issue by flushing the mm if reclaim is potentially currently batching TLB flushes. Other instances where a flush is required for a present pte should be ok as either the page lock is held preventing parallel reclaim or a page reference count is elevated preventing a parallel free leading to corruption. In the case of page_mkclean there isn't an obvious path that userspace could take advantage of without using the operations that are guarded by this patch. Other users such as gup as a race with reclaim looks just at PTEs. huge page variants should be ok as they don't race with reclaim. mincore only looks at PTEs. userfault also should be ok as if a parallel reclaim takes place, it will either fault the page back in or read some of the data before the flush occurs triggering a fault. Note that a variant of this patch was acked by Andy Lutomirski but this was for the x86 parts on top of his PCID work which didn't make the 4.13 merge window as expected. His ack is dropped from this version and there will be a follow-on patch on top of PCID that will include his ack. [akpm@linux-foundation.org: tweak comments] [akpm@linux-foundation.org: fix spello] Link: http://lkml.kernel.org/r/20170717155523.emckq2esjro6hf3z@suse.de Reported-by: Nadav Amit Signed-off-by: Mel Gorman Cc: Andy Lutomirski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/mm_types.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux') diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 2ccccbfcd532..36f4695aa604 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -503,6 +503,10 @@ struct mm_struct { * PROT_NONE or PROT_NUMA mapped page. */ bool tlb_flush_pending; +#endif +#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH + /* See flush_tlb_batched_pending() */ + bool tlb_flush_batched; #endif struct uprobes_state uprobes_state; #ifdef CONFIG_X86_INTEL_MPX -- cgit v1.2.3 From 9c83b97bdeabfea1f9c51c1f505ee14f13e4c628 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 10 Jan 2017 16:57:27 -0800 Subject: mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER [ Upstream commit bb1107f7c6052c863692a41f78c000db792334bf ] Andrey Konovalov has reported the following warning triggered by the syzkaller fuzzer. WARNING: CPU: 1 PID: 9935 at mm/page_alloc.c:3511 __alloc_pages_nodemask+0x159c/0x1e20 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 9935 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #34 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __alloc_pages_slowpath mm/page_alloc.c:3511 __alloc_pages_nodemask+0x159c/0x1e20 mm/page_alloc.c:3781 alloc_pages_current+0x1c7/0x6b0 mm/mempolicy.c:2072 alloc_pages include/linux/gfp.h:469 kmalloc_order+0x1f/0x70 mm/slab_common.c:1015 kmalloc_order_trace+0x1f/0x160 mm/slab_common.c:1026 kmalloc_large include/linux/slab.h:422 __kmalloc+0x210/0x2d0 mm/slub.c:3723 kmalloc include/linux/slab.h:495 ep_write_iter+0x167/0xb50 drivers/usb/gadget/legacy/inode.c:664 new_sync_write fs/read_write.c:499 __vfs_write+0x483/0x760 fs/read_write.c:512 vfs_write+0x170/0x4e0 fs/read_write.c:560 SYSC_write fs/read_write.c:607 SyS_write+0xfb/0x230 fs/read_write.c:599 entry_SYSCALL_64_fastpath+0x1f/0xc2 The issue is caused by a lack of size check for the request size in ep_write_iter which should be fixed. It, however, points to another problem, that SLUB defines KMALLOC_MAX_SIZE too large because the its KMALLOC_SHIFT_MAX is (MAX_ORDER + PAGE_SHIFT) which means that the resulting page allocator request might be MAX_ORDER which is too large (see __alloc_pages_slowpath). The same applies to the SLOB allocator which allows even larger sizes. Make sure that they are capped properly and never request more than MAX_ORDER order. Link: http://lkml.kernel.org/r/20161220130659.16461-2-mhocko@kernel.org Signed-off-by: Michal Hocko Reported-by: Andrey Konovalov Acked-by: Christoph Lameter Cc: Alexei Starovoitov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/slab.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/slab.h b/include/linux/slab.h index 2037a861e367..8a2a9ffaf5de 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -203,7 +203,7 @@ size_t ksize(const void *); * (PAGE_SIZE*2). Larger requests are passed to the page allocator. */ #define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1) -#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT) +#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1) #ifndef KMALLOC_SHIFT_LOW #define KMALLOC_SHIFT_LOW 3 #endif @@ -216,7 +216,7 @@ size_t ksize(const void *); * be allocated from the same page. */ #define KMALLOC_SHIFT_HIGH PAGE_SHIFT -#define KMALLOC_SHIFT_MAX 30 +#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1) #ifndef KMALLOC_SHIFT_LOW #define KMALLOC_SHIFT_LOW 3 #endif -- cgit v1.2.3 From bbe660db23e41647366039c1860cee0891fe9903 Mon Sep 17 00:00:00 2001 From: Jamie Iles Date: Tue, 10 Jan 2017 16:57:54 -0800 Subject: signal: protect SIGNAL_UNKILLABLE from unintentional clearing. [ Upstream commit 2d39b3cd34e6d323720d4c61bd714f5ae202c022 ] Since commit 00cd5c37afd5 ("ptrace: permit ptracing of /sbin/init") we can now trace init processes. init is initially protected with SIGNAL_UNKILLABLE which will prevent fatal signals such as SIGSTOP, but there are a number of paths during tracing where SIGNAL_UNKILLABLE can be implicitly cleared. This can result in init becoming stoppable/killable after tracing. For example, running: while true; do kill -STOP 1; done & strace -p 1 and then stopping strace and the kill loop will result in init being left in state TASK_STOPPED. Sending SIGCONT to init will resume it, but init will now respond to future SIGSTOP signals rather than ignoring them. Make sure that when setting SIGNAL_STOP_CONTINUED/SIGNAL_STOP_STOPPED that we don't clear SIGNAL_UNKILLABLE. Link: http://lkml.kernel.org/r/20170104122017.25047-1-jamie.iles@oracle.com Signed-off-by: Jamie Iles Acked-by: Oleg Nesterov Cc: Alexander Viro Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/sched.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 352213b360d7..eff7c1fad26f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -801,6 +801,16 @@ struct signal_struct { #define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */ +#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \ + SIGNAL_STOP_CONTINUED) + +static inline void signal_set_stop_flags(struct signal_struct *sig, + unsigned int flags) +{ + WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP)); + sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags; +} + /* If true, all threads except ->group_exit_task have pending SIGKILL */ static inline int signal_group_exit(const struct signal_struct *sig) { -- cgit v1.2.3 From 34a08ae493f1970d5ce80dd3812b8dba4e5cbe22 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 23 Jul 2017 08:36:15 -0400 Subject: workqueue: implicit ordered attribute should be overridable MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 0a94efb5acbb6980d7c9ab604372d93cd507e4d8 upstream. 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") automatically enabled ordered attribute for unbound workqueues w/ max_active == 1. Because ordered workqueues reject max_active and some attribute changes, this implicit ordered mode broke cases where the user creates an unbound workqueue w/ max_active == 1 and later explicitly changes the related attributes. This patch distinguishes explicit and implicit ordered setting and overrides from attribute changes if implict. Signed-off-by: Tejun Heo Fixes: 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") Cc: Holger Hoffstätte Signed-off-by: Greg Kroah-Hartman --- include/linux/workqueue.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 0197358f1e81..262d5c95dfc8 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -311,6 +311,7 @@ enum { __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */ __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */ + __WQ_ORDERED_EXPLICIT = 1 << 18, /* internal: alloc_ordered_workqueue() */ WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */ @@ -408,7 +409,8 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active, * Pointer to the allocated workqueue on success, %NULL on failure. */ #define alloc_ordered_workqueue(fmt, flags, args...) \ - alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args) + alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | \ + __WQ_ORDERED_EXPLICIT | (flags), 1, ##args) #define create_workqueue(name) \ alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name)) -- cgit v1.2.3