From 19e72d3abb63cb16d021a4066ce1a18880509e99 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 9 Feb 2017 17:28:50 -0800 Subject: configfs: Introduce config_item_get_unless_zero() Signed-off-by: Bart Van Assche [hch: minor style tweak] Signed-off-by: Christoph Hellwig --- include/linux/configfs.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/configfs.h b/include/linux/configfs.h index 2319b8c108e8..c96709049683 100644 --- a/include/linux/configfs.h +++ b/include/linux/configfs.h @@ -74,7 +74,8 @@ extern void config_item_init_type_name(struct config_item *item, const char *name, struct config_item_type *type); -extern struct config_item * config_item_get(struct config_item *); +extern struct config_item *config_item_get(struct config_item *); +extern struct config_item *config_item_get_unless_zero(struct config_item *); extern void config_item_put(struct config_item *); struct config_item_type { -- cgit v1.2.3 From dc9edc44de6cd7cc8cc7f5b36c1adb221eda3207 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 14 Jun 2017 13:27:50 -0600 Subject: block: Fix a blk_exit_rl() regression Avoid that the following complaint is reported: BUG: sleeping function called from invalid context at kernel/workqueue.c:2790 in_atomic(): 1, irqs_disabled(): 0, pid: 41, name: rcuop/3 1 lock held by rcuop/3/41: #0: (rcu_callback){......}, at: [] rcu_nocb_kthread+0x282/0x500 Call Trace: dump_stack+0x86/0xcf ___might_sleep+0x174/0x260 __might_sleep+0x4a/0x80 flush_work+0x7e/0x2e0 __cancel_work_timer+0x143/0x1c0 cancel_work_sync+0x10/0x20 blk_throtl_exit+0x25/0x60 blkcg_exit_queue+0x35/0x40 blk_release_queue+0x42/0x130 kobject_put+0xa9/0x190 This happens since we invoke callbacks that need to block from the queue release handler. Fix this by pushing the final release to a workqueue. Reported-by: Ross Zwisler Fixes: commit b425e5049258 ("block: Avoid that blk_exit_rl() triggers a use-after-free") Signed-off-by: Bart Van Assche Tested-by: Ross Zwisler Updated changelog Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index ab92c4ea138b..b74a3edcb3da 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -586,6 +586,8 @@ struct request_queue { size_t cmd_size; void *rq_alloc_data; + + struct work_struct release_work; }; #define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */ -- cgit v1.2.3 From c926820085437a27b27e78996b2c7a5ad94e8055 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 15 Jun 2017 13:46:00 +0200 Subject: firmware: dmi_scan: Make dmi_walk and dmi_walk_early return real error codes Currently they return -1 on error, which will confuse callers if they try to interpret it as a normal negative error code. Signed-off-by: Andy Lutomirski Signed-off-by: Darren Hart (VMware) Signed-off-by: Jean Delvare --- include/linux/dmi.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/dmi.h b/include/linux/dmi.h index 5e9c74cf8894..9bbf21a516e4 100644 --- a/include/linux/dmi.h +++ b/include/linux/dmi.h @@ -136,7 +136,7 @@ static inline int dmi_name_in_vendors(const char *s) { return 0; } static inline int dmi_name_in_serial(const char *s) { return 0; } #define dmi_available 0 static inline int dmi_walk(void (*decode)(const struct dmi_header *, void *), - void *private_data) { return -1; } + void *private_data) { return -ENXIO; } static inline bool dmi_match(enum dmi_field f, const char *str) { return false; } static inline void dmi_memdev_name(u16 handle, const char **bank, -- cgit v1.2.3 From 1be7107fbe18eed3e319a6c3e83c78254b693acb Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 19 Jun 2017 04:03:24 -0700 Subject: mm: larger stack guard gap, between vmas Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds --- include/linux/mm.h | 53 +++++++++++++++++++++++++---------------------------- 1 file changed, 25 insertions(+), 28 deletions(-) (limited to 'include/linux') diff --git a/include/linux/mm.h b/include/linux/mm.h index b892e95d4929..6f543a47fc92 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1393,12 +1393,6 @@ int clear_page_dirty_for_io(struct page *page); int get_cmdline(struct task_struct *task, char *buffer, int buflen); -/* Is the vma a continuation of the stack vma above it? */ -static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr) -{ - return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN); -} - static inline bool vma_is_anonymous(struct vm_area_struct *vma) { return !vma->vm_ops; @@ -1414,28 +1408,6 @@ bool vma_is_shmem(struct vm_area_struct *vma); static inline bool vma_is_shmem(struct vm_area_struct *vma) { return false; } #endif -static inline int stack_guard_page_start(struct vm_area_struct *vma, - unsigned long addr) -{ - return (vma->vm_flags & VM_GROWSDOWN) && - (vma->vm_start == addr) && - !vma_growsdown(vma->vm_prev, addr); -} - -/* Is the vma a continuation of the stack vma below it? */ -static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr) -{ - return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP); -} - -static inline int stack_guard_page_end(struct vm_area_struct *vma, - unsigned long addr) -{ - return (vma->vm_flags & VM_GROWSUP) && - (vma->vm_end == addr) && - !vma_growsup(vma->vm_next, addr); -} - int vma_is_stack_for_current(struct vm_area_struct *vma); extern unsigned long move_page_tables(struct vm_area_struct *vma, @@ -2222,6 +2194,7 @@ void page_cache_async_readahead(struct address_space *mapping, pgoff_t offset, unsigned long size); +extern unsigned long stack_guard_gap; /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */ extern int expand_stack(struct vm_area_struct *vma, unsigned long address); @@ -2250,6 +2223,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m return vma; } +static inline unsigned long vm_start_gap(struct vm_area_struct *vma) +{ + unsigned long vm_start = vma->vm_start; + + if (vma->vm_flags & VM_GROWSDOWN) { + vm_start -= stack_guard_gap; + if (vm_start > vma->vm_start) + vm_start = 0; + } + return vm_start; +} + +static inline unsigned long vm_end_gap(struct vm_area_struct *vma) +{ + unsigned long vm_end = vma->vm_end; + + if (vma->vm_flags & VM_GROWSUP) { + vm_end += stack_guard_gap; + if (vm_end < vma->vm_end) + vm_end = -PAGE_SIZE; + } + return vm_end; +} + static inline unsigned long vma_pages(struct vm_area_struct *vma) { return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; -- cgit v1.2.3