From 2b059d0d1e624adc6e69a754bc48057f8bf459dc Mon Sep 17 00:00:00 2001 From: Pei Xiao Date: Wed, 23 Oct 2024 14:21:17 +0800 Subject: [PATCH 1/2] slub/kunit: fix a WARNING due to unwrapped __kmalloc_cache_noprof 'modprobe slub_kunit' will have a warning as shown below. The root cause is that __kmalloc_cache_noprof was directly used, which resulted in no alloc_tag being allocated. This caused current->alloc_tag to be null, leading to a warning in alloc_tag_add_check. Let's add an alloc_hook layer to __kmalloc_cache_noprof specifically within lib/slub_kunit.c, which is the only user of this internal slub function outside kmalloc implementation itself. [58162.947016] WARNING: CPU: 2 PID: 6210 at ./include/linux/alloc_tag.h:125 alloc_tagging_slab_alloc_hook+0x268/0x27c [58162.957721] Call trace: [58162.957919] alloc_tagging_slab_alloc_hook+0x268/0x27c [58162.958286] __kmalloc_cache_noprof+0x14c/0x344 [58162.958615] test_kmalloc_redzone_access+0x50/0x10c [slub_kunit] [58162.959045] kunit_try_run_case+0x74/0x184 [kunit] [58162.959401] kunit_generic_run_threadfn_adapter+0x2c/0x4c [kunit] [58162.959841] kthread+0x10c/0x118 [58162.960093] ret_from_fork+0x10/0x20 [58162.960363] ---[ end trace 0000000000000000 ]--- Signed-off-by: Pei Xiao Fixes: a0a44d9175b3 ("mm, slab: don't wrap internal functions with alloc_hooks()") Signed-off-by: Vlastimil Babka --- lib/slub_kunit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c index 80e39f003344..33564f965958 100644 --- a/lib/slub_kunit.c +++ b/lib/slub_kunit.c @@ -141,7 +141,7 @@ static void test_kmalloc_redzone_access(struct kunit *test) { struct kmem_cache *s = test_kmem_cache_create("TestSlub_RZ_kmalloc", 32, SLAB_KMALLOC|SLAB_STORE_USER|SLAB_RED_ZONE); - u8 *p = __kmalloc_cache_noprof(s, GFP_KERNEL, 18); + u8 *p = alloc_hooks(__kmalloc_cache_noprof(s, GFP_KERNEL, 18)); kasan_disable_current(); From 704573851b51808b45dae2d62059d1d8189138a2 Mon Sep 17 00:00:00 2001 From: Qun-Wei Lin Date: Fri, 25 Oct 2024 16:58:11 +0800 Subject: [PATCH 2/2] mm: krealloc: Fix MTE false alarm in __do_krealloc This patch addresses an issue introduced by commit 1a83a716ec233 ("mm: krealloc: consider spare memory for __GFP_ZERO") which causes MTE (Memory Tagging Extension) to falsely report a slab-out-of-bounds error. The problem occurs when zeroing out spare memory in __do_krealloc. The original code only considered software-based KASAN and did not account for MTE. It does not reset the KASAN tag before calling memset, leading to a mismatch between the pointer tag and the memory tag, resulting in a false positive. Example of the error: ================================================================== swapper/0: BUG: KASAN: slab-out-of-bounds in __memset+0x84/0x188 swapper/0: Write at addr f4ffff8005f0fdf0 by task swapper/0/1 swapper/0: Pointer tag: [f4], memory tag: [fe] swapper/0: swapper/0: CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12. swapper/0: Hardware name: MT6991(ENG) (DT) swapper/0: Call trace: swapper/0: dump_backtrace+0xfc/0x17c swapper/0: show_stack+0x18/0x28 swapper/0: dump_stack_lvl+0x40/0xa0 swapper/0: print_report+0x1b8/0x71c swapper/0: kasan_report+0xec/0x14c swapper/0: __do_kernel_fault+0x60/0x29c swapper/0: do_bad_area+0x30/0xdc swapper/0: do_tag_check_fault+0x20/0x34 swapper/0: do_mem_abort+0x58/0x104 swapper/0: el1_abort+0x3c/0x5c swapper/0: el1h_64_sync_handler+0x80/0xcc swapper/0: el1h_64_sync+0x68/0x6c swapper/0: __memset+0x84/0x188 swapper/0: btf_populate_kfunc_set+0x280/0x3d8 swapper/0: __register_btf_kfunc_id_set+0x43c/0x468 swapper/0: register_btf_kfunc_id_set+0x48/0x60 swapper/0: register_nf_nat_bpf+0x1c/0x40 swapper/0: nf_nat_init+0xc0/0x128 swapper/0: do_one_initcall+0x184/0x464 swapper/0: do_initcall_level+0xdc/0x1b0 swapper/0: do_initcalls+0x70/0xc0 swapper/0: do_basic_setup+0x1c/0x28 swapper/0: kernel_init_freeable+0x144/0x1b8 swapper/0: kernel_init+0x20/0x1a8 swapper/0: ret_from_fork+0x10/0x20 ================================================================== Fixes: 1a83a716ec233 ("mm: krealloc: consider spare memory for __GFP_ZERO") Signed-off-by: Qun-Wei Lin Acked-by: David Rientjes Signed-off-by: Vlastimil Babka --- mm/slab_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 3d26c257ed8b..552b92dfdac7 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1209,7 +1209,7 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags) /* Zero out spare memory. */ if (want_init_on_alloc(flags)) { kasan_disable_current(); - memset((void *)p + new_size, 0, ks - new_size); + memset(kasan_reset_tag(p) + new_size, 0, ks - new_size); kasan_enable_current(); }