![Dmitry Vyukov](/assets/img/avatar_default.png)
I observed false KSAN positives in the sctp code, when sctp uses jprobe_return() in jsctp_sf_eat_sack(). The stray 0xf4 in shadow memory are stack redzones: [ ] ================================================================== [ ] BUG: KASAN: stack-out-of-bounds in memcmp+0xe9/0x150 at addr ffff88005e48f480 [ ] Read of size 1 by task syz-executor/18535 [ ] page:ffffea00017923c0 count:0 mapcount:0 mapping: (null) index:0x0 [ ] flags: 0x1fffc0000000000() [ ] page dumped because: kasan: bad access detected [ ] CPU: 1 PID: 18535 Comm: syz-executor Not tainted 4.8.0+ #28 [ ] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ ] ffff88005e48f2d0 ffffffff82d2b849 ffffffff0bc91e90 fffffbfff10971e8 [ ] ffffed000bc91e90 ffffed000bc91e90 0000000000000001 0000000000000000 [ ] ffff88005e48f480 ffff88005e48f350 ffffffff817d3169 ffff88005e48f370 [ ] Call Trace: [ ] [<ffffffff82d2b849>] dump_stack+0x12e/0x185 [ ] [<ffffffff817d3169>] kasan_report+0x489/0x4b0 [ ] [<ffffffff817d31a9>] __asan_report_load1_noabort+0x19/0x20 [ ] [<ffffffff82d49529>] memcmp+0xe9/0x150 [ ] [<ffffffff82df7486>] depot_save_stack+0x176/0x5c0 [ ] [<ffffffff817d2031>] save_stack+0xb1/0xd0 [ ] [<ffffffff817d27f2>] kasan_slab_free+0x72/0xc0 [ ] [<ffffffff817d05b8>] kfree+0xc8/0x2a0 [ ] [<ffffffff85b03f19>] skb_free_head+0x79/0xb0 [ ] [<ffffffff85b0900a>] skb_release_data+0x37a/0x420 [ ] [<ffffffff85b090ff>] skb_release_all+0x4f/0x60 [ ] [<ffffffff85b11348>] consume_skb+0x138/0x370 [ ] [<ffffffff8676ad7b>] sctp_chunk_put+0xcb/0x180 [ ] [<ffffffff8676ae88>] sctp_chunk_free+0x58/0x70 [ ] [<ffffffff8677fa5f>] sctp_inq_pop+0x68f/0xef0 [ ] [<ffffffff8675ee36>] sctp_assoc_bh_rcv+0xd6/0x4b0 [ ] [<ffffffff8677f2c1>] sctp_inq_push+0x131/0x190 [ ] [<ffffffff867bad69>] sctp_backlog_rcv+0xe9/0xa20 [ ... ] [ ] Memory state around the buggy address: [ ] ffff88005e48f380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ ] ffff88005e48f400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ ] >ffff88005e48f480: f4 f4 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ ] ^ [ ] ffff88005e48f500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ ] ffff88005e48f580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ ] ================================================================== KASAN stack instrumentation poisons stack redzones on function entry and unpoisons them on function exit. If a function exits abnormally (e.g. with a longjmp like jprobe_return()), stack redzones are left poisoned. Later this leads to random KASAN false reports. Unpoison stack redzones in the frames we are going to jump over before doing actual longjmp in jprobe_return(). Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Alexander Potapenko <glider@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: kasan-dev@googlegroups.com Cc: surovegin@google.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/1476454043-101898-1-git-send-email-dvyukov@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
135 lines
4.4 KiB
C
135 lines
4.4 KiB
C
#ifndef _LINUX_KASAN_H
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#define _LINUX_KASAN_H
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#include <linux/sched.h>
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#include <linux/types.h>
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struct kmem_cache;
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struct page;
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struct vm_struct;
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#ifdef CONFIG_KASAN
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#define KASAN_SHADOW_SCALE_SHIFT 3
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#include <asm/kasan.h>
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#include <asm/pgtable.h>
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extern unsigned char kasan_zero_page[PAGE_SIZE];
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extern pte_t kasan_zero_pte[PTRS_PER_PTE];
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extern pmd_t kasan_zero_pmd[PTRS_PER_PMD];
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extern pud_t kasan_zero_pud[PTRS_PER_PUD];
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void kasan_populate_zero_shadow(const void *shadow_start,
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const void *shadow_end);
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static inline void *kasan_mem_to_shadow(const void *addr)
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{
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return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
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+ KASAN_SHADOW_OFFSET;
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}
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/* Enable reporting bugs after kasan_disable_current() */
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static inline void kasan_enable_current(void)
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{
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current->kasan_depth++;
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}
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/* Disable reporting bugs for current task */
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static inline void kasan_disable_current(void)
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{
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current->kasan_depth--;
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}
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void kasan_unpoison_shadow(const void *address, size_t size);
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void kasan_unpoison_task_stack(struct task_struct *task);
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void kasan_unpoison_stack_above_sp_to(const void *watermark);
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void kasan_alloc_pages(struct page *page, unsigned int order);
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void kasan_free_pages(struct page *page, unsigned int order);
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void kasan_cache_create(struct kmem_cache *cache, size_t *size,
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unsigned long *flags);
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void kasan_cache_shrink(struct kmem_cache *cache);
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void kasan_cache_destroy(struct kmem_cache *cache);
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void kasan_poison_slab(struct page *page);
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void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
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void kasan_poison_object_data(struct kmem_cache *cache, void *object);
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void kasan_init_slab_obj(struct kmem_cache *cache, const void *object);
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void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
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void kasan_kfree_large(const void *ptr);
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void kasan_poison_kfree(void *ptr);
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void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size,
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gfp_t flags);
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void kasan_krealloc(const void *object, size_t new_size, gfp_t flags);
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void kasan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
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bool kasan_slab_free(struct kmem_cache *s, void *object);
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struct kasan_cache {
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int alloc_meta_offset;
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int free_meta_offset;
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};
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int kasan_module_alloc(void *addr, size_t size);
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void kasan_free_shadow(const struct vm_struct *vm);
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size_t ksize(const void *);
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static inline void kasan_unpoison_slab(const void *ptr) { ksize(ptr); }
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size_t kasan_metadata_size(struct kmem_cache *cache);
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#else /* CONFIG_KASAN */
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static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
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static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
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static inline void kasan_unpoison_stack_above_sp_to(const void *watermark) {}
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static inline void kasan_enable_current(void) {}
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static inline void kasan_disable_current(void) {}
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static inline void kasan_alloc_pages(struct page *page, unsigned int order) {}
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static inline void kasan_free_pages(struct page *page, unsigned int order) {}
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static inline void kasan_cache_create(struct kmem_cache *cache,
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size_t *size,
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unsigned long *flags) {}
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static inline void kasan_cache_shrink(struct kmem_cache *cache) {}
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static inline void kasan_cache_destroy(struct kmem_cache *cache) {}
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static inline void kasan_poison_slab(struct page *page) {}
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static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
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void *object) {}
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static inline void kasan_poison_object_data(struct kmem_cache *cache,
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void *object) {}
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static inline void kasan_init_slab_obj(struct kmem_cache *cache,
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const void *object) {}
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static inline void kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags) {}
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static inline void kasan_kfree_large(const void *ptr) {}
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static inline void kasan_poison_kfree(void *ptr) {}
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static inline void kasan_kmalloc(struct kmem_cache *s, const void *object,
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size_t size, gfp_t flags) {}
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static inline void kasan_krealloc(const void *object, size_t new_size,
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gfp_t flags) {}
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static inline void kasan_slab_alloc(struct kmem_cache *s, void *object,
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gfp_t flags) {}
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static inline bool kasan_slab_free(struct kmem_cache *s, void *object)
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{
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return false;
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}
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static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
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static inline void kasan_free_shadow(const struct vm_struct *vm) {}
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static inline void kasan_unpoison_slab(const void *ptr) { }
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static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
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#endif /* CONFIG_KASAN */
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#endif /* LINUX_KASAN_H */
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