From b92a953cb7f727c42a15ac2ea59bf3cf9c39370d Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 23 Sep 2019 15:34:16 -0700 Subject: [PATCH] lib/test_kasan.c: add roundtrip tests In several places we need to be able to operate on pointers which have gone via a roundtrip: virt -> {phys,page} -> virt With KASAN_SW_TAGS, we can't preserve the tag for SLUB objects, and the {phys,page} -> virt conversion will use KASAN_TAG_KERNEL. This patch adds tests to ensure that this works as expected, without false positives which have recently been spotted [1,2] in testing. [1] https://lore.kernel.org/linux-arm-kernel/20190819114420.2535-1-walter-zh.wu@mediatek.com/ [2] https://lore.kernel.org/linux-arm-kernel/20190819132347.GB9927@lakrids.cambridge.arm.com/ [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20190821153927.28630-1-mark.rutland@arm.com Signed-off-by: Mark Rutland Reviewed-by: Andrey Konovalov Tested-by: Andrey Konovalov Acked-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/lib/test_kasan.c b/lib/test_kasan.c index b63b367a94e8..49cc4d570a40 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -18,6 +18,9 @@ #include #include #include +#include + +#include /* * Note: test functions are marked noinline so that their names appear in @@ -337,6 +340,42 @@ static noinline void __init kmalloc_uaf2(void) kfree(ptr2); } +static noinline void __init kfree_via_page(void) +{ + char *ptr; + size_t size = 8; + struct page *page; + unsigned long offset; + + pr_info("invalid-free false positive (via page)\n"); + ptr = kmalloc(size, GFP_KERNEL); + if (!ptr) { + pr_err("Allocation failed\n"); + return; + } + + page = virt_to_page(ptr); + offset = offset_in_page(ptr); + kfree(page_address(page) + offset); +} + +static noinline void __init kfree_via_phys(void) +{ + char *ptr; + size_t size = 8; + phys_addr_t phys; + + pr_info("invalid-free false positive (via phys)\n"); + ptr = kmalloc(size, GFP_KERNEL); + if (!ptr) { + pr_err("Allocation failed\n"); + return; + } + + phys = virt_to_phys(ptr); + kfree(phys_to_virt(phys)); +} + static noinline void __init kmem_cache_oob(void) { char *p; @@ -737,6 +776,8 @@ static int __init kmalloc_tests_init(void) kmalloc_uaf(); kmalloc_uaf_memset(); kmalloc_uaf2(); + kfree_via_page(); + kfree_via_phys(); kmem_cache_oob(); memcg_accounted_kmem_cache(); kasan_stack_oob();