[PATCH v2] kasan, mempool: don't store free stacktrace in io_alloc_cache objects.
From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Date: 2025-01-27 15:05:13
Also in:
io-uring, linux-mm, lkml, stable
Subsystem:
io_uring, kasan, memory management, networking [general], slab allocator, the rest · Maintainers:
Jens Axboe, Andrey Ryabinin, Andrew Morton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Vlastimil Babka, Harry Yoo, Linus Torvalds
Running the testcase liburing/accept-reust.t with CONFIG_KASAN=y and
CONFIG_KASAN_EXTRA_INFO=y leads to the following crash:
Unable to handle kernel paging request at virtual address 00000c6455008008
...
pc : __kasan_mempool_unpoison_object+0x38/0x170
lr : io_netmsg_cache_free+0x8c/0x180
...
Call trace:
__kasan_mempool_unpoison_object+0x38/0x170 (P)
io_netmsg_cache_free+0x8c/0x180
io_ring_exit_work+0xd4c/0x13a0
process_one_work+0x52c/0x1000
worker_thread+0x830/0xdc0
kthread+0x2bc/0x348
ret_from_fork+0x10/0x20
Since the commit b556a462eb8d ("kasan: save free stack traces for slab mempools")
kasan_mempool_poison_object() stores some info inside an object.
It was expected that the object must be reinitialized after
kasan_mempool_unpoison_object() call, and this is what happens in the
most of use cases.
However io_uring code expects that io_alloc_cache_put/get doesn't modify
the object, so kasan_mempool_poison_object() end up corrupting it leading
to crash later.
Add @notrack argument to kasan_mempool_poison_object() call to tell
KASAN to avoid storing info in objects for io_uring use case.
Reported-by: lizetao <redacted>
Closes: https://lkml.kernel.org/r/ec2a6ca08c614c10853fbb1270296ac4@huawei.com
Fixes: b556a462eb8d ("kasan: save free stack traces for slab mempools")
Cc: stable@vger.kernel.org
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
---
- Changes since v1:
s/true/false @notrack in __kasan_slab_free() per @andreyknvl
include/linux/kasan.h | 13 +++++++------
io_uring/alloc_cache.h | 2 +-
io_uring/net.c | 2 +-
io_uring/rw.c | 2 +-
mm/kasan/common.c | 11 ++++++-----
mm/mempool.c | 2 +-
net/core/skbuff.c | 2 +-
7 files changed, 18 insertions(+), 16 deletions(-)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 890011071f2b..4d0bf4af399d 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h@@ -328,18 +328,19 @@ static __always_inline void kasan_mempool_unpoison_pages(struct page *page, __kasan_mempool_unpoison_pages(page, order, _RET_IP_); } -bool __kasan_mempool_poison_object(void *ptr, unsigned long ip); +bool __kasan_mempool_poison_object(void *ptr, bool notrack, unsigned long ip); /** * kasan_mempool_poison_object - Check and poison a mempool slab allocation. * @ptr: Pointer to the slab allocation. + * @notrack: Don't record stack trace of this call in the object. * * This function is intended for kernel subsystems that cache slab allocations * to reuse them instead of freeing them back to the slab allocator (e.g. * mempool). * * This function poisons a slab allocation and saves a free stack trace for it - * without initializing the allocation's memory and without putting it into the - * quarantine (for the Generic mode). + * (if @notrack == false) without initializing the allocation's memory and + * without putting it into the quarantine (for the Generic mode). * * This function also performs checks to detect double-free and invalid-free * bugs and reports them. The caller can use the return value of this function
@@ -354,10 +355,10 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip); * * Return: true if the allocation can be safely reused; false otherwise. */ -static __always_inline bool kasan_mempool_poison_object(void *ptr) +static __always_inline bool kasan_mempool_poison_object(void *ptr, bool notrack) { if (kasan_enabled()) - return __kasan_mempool_poison_object(ptr, _RET_IP_); + return __kasan_mempool_poison_object(ptr, notrack, _RET_IP_); return true; }
@@ -456,7 +457,7 @@ static inline bool kasan_mempool_poison_pages(struct page *page, unsigned int or return true; } static inline void kasan_mempool_unpoison_pages(struct page *page, unsigned int order) {} -static inline bool kasan_mempool_poison_object(void *ptr) +static inline bool kasan_mempool_poison_object(void *ptr, bool notrack) { return true; }
diff --git a/io_uring/alloc_cache.h b/io_uring/alloc_cache.h
index a3a8cfec32ce..dd508dddea33 100644
--- a/io_uring/alloc_cache.h
+++ b/io_uring/alloc_cache.h@@ -10,7 +10,7 @@ static inline bool io_alloc_cache_put(struct io_alloc_cache *cache, void *entry) { if (cache->nr_cached < cache->max_cached) { - if (!kasan_mempool_poison_object(entry)) + if (!kasan_mempool_poison_object(entry, true)) return false; cache->entries[cache->nr_cached++] = entry; return true;
diff --git a/io_uring/net.c b/io_uring/net.c
index 85f55fbc25c9..a954e37c7fd3 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c@@ -149,7 +149,7 @@ static void io_netmsg_recycle(struct io_kiocb *req, unsigned int issue_flags) iov = hdr->free_iov; if (io_alloc_cache_put(&req->ctx->netmsg_cache, hdr)) { if (iov) - kasan_mempool_poison_object(iov); + kasan_mempool_poison_object(iov, true); req->async_data = NULL; req->flags &= ~REQ_F_ASYNC_DATA; }
diff --git a/io_uring/rw.c b/io_uring/rw.c
index a9a2733be842..cba475003ba7 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c@@ -167,7 +167,7 @@ static void io_rw_recycle(struct io_kiocb *req, unsigned int issue_flags) iov = rw->free_iovec; if (io_alloc_cache_put(&req->ctx->rw_cache, rw)) { if (iov) - kasan_mempool_poison_object(iov); + kasan_mempool_poison_object(iov, true); req->async_data = NULL; req->flags &= ~REQ_F_ASYNC_DATA; }
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index ed4873e18c75..f08752dcd50b 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c@@ -230,7 +230,8 @@ static bool check_slab_allocation(struct kmem_cache *cache, void *object, } static inline void poison_slab_object(struct kmem_cache *cache, void *object, - bool init, bool still_accessible) + bool init, bool still_accessible, + bool notrack) { void *tagged_object = object;
@@ -243,7 +244,7 @@ static inline void poison_slab_object(struct kmem_cache *cache, void *object, kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE), KASAN_SLAB_FREE, init); - if (kasan_stack_collection_enabled()) + if (kasan_stack_collection_enabled() && !notrack) kasan_save_free_info(cache, tagged_object); }
@@ -261,7 +262,7 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object, bool init, if (!kasan_arch_is_ready() || is_kfence_address(object)) return false; - poison_slab_object(cache, object, init, still_accessible); + poison_slab_object(cache, object, init, still_accessible, false); /* * If the object is put into quarantine, do not let slab put the object
@@ -495,7 +496,7 @@ void __kasan_mempool_unpoison_pages(struct page *page, unsigned int order, __kasan_unpoison_pages(page, order, false); } -bool __kasan_mempool_poison_object(void *ptr, unsigned long ip) +bool __kasan_mempool_poison_object(void *ptr, bool notrack, unsigned long ip) { struct folio *folio = virt_to_folio(ptr); struct slab *slab;
@@ -519,7 +520,7 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip) if (check_slab_allocation(slab->slab_cache, ptr, ip)) return false; - poison_slab_object(slab->slab_cache, ptr, false, false); + poison_slab_object(slab->slab_cache, ptr, false, false, notrack); return true; }
diff --git a/mm/mempool.c b/mm/mempool.c
index 3223337135d0..283df5d2b995 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c@@ -115,7 +115,7 @@ static inline void poison_element(mempool_t *pool, void *element) static __always_inline bool kasan_poison_element(mempool_t *pool, void *element) { if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) - return kasan_mempool_poison_object(element); + return kasan_mempool_poison_object(element, false); else if (pool->alloc == mempool_alloc_pages) return kasan_mempool_poison_pages(element, (unsigned long)pool->pool_data);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a441613a1e6c..c9f58a698bb7 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -1457,7 +1457,7 @@ static void napi_skb_cache_put(struct sk_buff *skb) struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache); u32 i; - if (!kasan_mempool_poison_object(skb)) + if (!kasan_mempool_poison_object(skb, false)) return; local_lock_nested_bh(&napi_alloc_cache.bh_lock);
--
2.45.3