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c993ee0f9f
In watch_queue_set_filter(), there are a couple of places where we check
that the filter type value does not exceed what the type_filter bitmap
can hold. One place calculates the number of bits by:
if (tf[i].type >= sizeof(wfilter->type_filter) * 8)
which is fine, but the second does:
if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG)
which is not. This can lead to a couple of out-of-bounds writes due to
a too-large type:
(1) __set_bit() on wfilter->type_filter
(2) Writing more elements in wfilter->filters[] than we allocated.
Fix this by just using the proper WATCH_TYPE__NR instead, which is the
number of types we actually know about.
The bug may cause an oops looking something like:
BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740
Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611
...
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x59
print_address_description.constprop.0+0x1f/0x150
...
kasan_report.cold+0x7f/0x11b
...
watch_queue_set_filter+0x659/0x740
...
__x64_sys_ioctl+0x127/0x190
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
Allocated by task 611:
kasan_save_stack+0x1e/0x40
__kasan_kmalloc+0x81/0xa0
watch_queue_set_filter+0x23a/0x740
__x64_sys_ioctl+0x127/0x190
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff88800d2c66a0
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 28 bytes inside of
32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
134 lines
3.8 KiB
C
134 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* User-mappable watch queue
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*
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* Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* See Documentation/watch_queue.rst
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*/
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#ifndef _LINUX_WATCH_QUEUE_H
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#define _LINUX_WATCH_QUEUE_H
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#include <uapi/linux/watch_queue.h>
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#include <linux/kref.h>
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#include <linux/rcupdate.h>
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#ifdef CONFIG_WATCH_QUEUE
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struct cred;
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struct watch_type_filter {
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enum watch_notification_type type;
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__u32 subtype_filter[1]; /* Bitmask of subtypes to filter on */
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__u32 info_filter; /* Filter on watch_notification::info */
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__u32 info_mask; /* Mask of relevant bits in info_filter */
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};
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struct watch_filter {
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union {
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struct rcu_head rcu;
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/* Bitmask of accepted types */
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DECLARE_BITMAP(type_filter, WATCH_TYPE__NR);
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};
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u32 nr_filters; /* Number of filters */
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struct watch_type_filter filters[];
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};
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struct watch_queue {
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struct rcu_head rcu;
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struct watch_filter __rcu *filter;
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struct pipe_inode_info *pipe; /* The pipe we're using as a buffer */
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struct hlist_head watches; /* Contributory watches */
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struct page **notes; /* Preallocated notifications */
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unsigned long *notes_bitmap; /* Allocation bitmap for notes */
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struct kref usage; /* Object usage count */
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spinlock_t lock;
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unsigned int nr_notes; /* Number of notes */
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unsigned int nr_pages; /* Number of pages in notes[] */
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bool defunct; /* T when queues closed */
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};
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/*
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* Representation of a watch on an object.
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*/
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struct watch {
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union {
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struct rcu_head rcu;
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u32 info_id; /* ID to be OR'd in to info field */
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};
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struct watch_queue __rcu *queue; /* Queue to post events to */
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struct hlist_node queue_node; /* Link in queue->watches */
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struct watch_list __rcu *watch_list;
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struct hlist_node list_node; /* Link in watch_list->watchers */
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const struct cred *cred; /* Creds of the owner of the watch */
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void *private; /* Private data for the watched object */
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u64 id; /* Internal identifier */
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struct kref usage; /* Object usage count */
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};
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/*
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* List of watches on an object.
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*/
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struct watch_list {
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struct rcu_head rcu;
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struct hlist_head watchers;
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void (*release_watch)(struct watch *);
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spinlock_t lock;
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};
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extern void __post_watch_notification(struct watch_list *,
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struct watch_notification *,
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const struct cred *,
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u64);
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extern struct watch_queue *get_watch_queue(int);
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extern void put_watch_queue(struct watch_queue *);
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extern void init_watch(struct watch *, struct watch_queue *);
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extern int add_watch_to_object(struct watch *, struct watch_list *);
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extern int remove_watch_from_object(struct watch_list *, struct watch_queue *, u64, bool);
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extern long watch_queue_set_size(struct pipe_inode_info *, unsigned int);
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extern long watch_queue_set_filter(struct pipe_inode_info *,
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struct watch_notification_filter __user *);
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extern int watch_queue_init(struct pipe_inode_info *);
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extern void watch_queue_clear(struct watch_queue *);
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static inline void init_watch_list(struct watch_list *wlist,
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void (*release_watch)(struct watch *))
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{
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INIT_HLIST_HEAD(&wlist->watchers);
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spin_lock_init(&wlist->lock);
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wlist->release_watch = release_watch;
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}
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static inline void post_watch_notification(struct watch_list *wlist,
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struct watch_notification *n,
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const struct cred *cred,
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u64 id)
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{
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if (unlikely(wlist))
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__post_watch_notification(wlist, n, cred, id);
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}
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static inline void remove_watch_list(struct watch_list *wlist, u64 id)
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{
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if (wlist) {
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remove_watch_from_object(wlist, NULL, id, true);
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kfree_rcu(wlist, rcu);
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}
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}
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/**
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* watch_sizeof - Calculate the information part of the size of a watch record,
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* given the structure size.
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*/
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#define watch_sizeof(STRUCT) (sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT)
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#else
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static inline int watch_queue_init(struct pipe_inode_info *pipe)
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{
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return -ENOPKG;
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}
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#endif
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#endif /* _LINUX_WATCH_QUEUE_H */
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