| Message ID | 20241011071657.3032690-1-snovitoll@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kasan: migrate copy_user_test to kunit | expand |
On Fri, Oct 11, 2024 at 12:16 PM Sabyrzhan Tasbolatov <snovitoll@gmail.com> wrote: > > Migrate the copy_user_test to the KUnit framework to verify out-of-bound > detection via KASAN reports in copy_from_user(), copy_to_user() and > their static functions. > > This is the last migrated test in kasan_test_module.c, therefore delete > the file. > > In order to detect OOB access in strncpy_from_user(), we need to move > kasan_check_write() to the function beginning to cover > if (can_do_masked_user_access()) {...} branch as well. > > Reported-by: Andrey Konovalov <andreyknvl@gmail.com> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=212205 > Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com> > --- > lib/strncpy_from_user.c | 3 +- > mm/kasan/kasan_test_c.c | 39 +++++++++++++++++ > mm/kasan/kasan_test_module.c | 81 ------------------------------------ > 3 files changed, 41 insertions(+), 82 deletions(-) > delete mode 100644 mm/kasan/kasan_test_module.c > > diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c > index 989a12a67872..55c33e4f3c70 100644 > --- a/lib/strncpy_from_user.c > +++ b/lib/strncpy_from_user.c > @@ -120,6 +120,8 @@ long strncpy_from_user(char *dst, const char __user *src, long count) > if (unlikely(count <= 0)) > return 0; > > + kasan_check_write(dst, count); > + > if (can_do_masked_user_access()) { > long retval; > > @@ -142,7 +144,6 @@ long strncpy_from_user(char *dst, const char __user *src, long count) > if (max > count) > max = count; > > - kasan_check_write(dst, count); > check_object_size(dst, count, false); > if (user_read_access_begin(src, max)) { > retval = do_strncpy_from_user(dst, src, count, max); > diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c > index a181e4780d9d..e71a16d0dfb9 100644 > --- a/mm/kasan/kasan_test_c.c > +++ b/mm/kasan/kasan_test_c.c > @@ -1954,6 +1954,44 @@ static void rust_uaf(struct kunit *test) > KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf()); > } > > +static void copy_user_test_oob(struct kunit *test) > +{ > + char *kmem; > + char __user *usermem; > + unsigned long useraddr; > + size_t size = 128 - KASAN_GRANULE_SIZE; > + int __maybe_unused unused; > + > + kmem = kunit_kmalloc(test, size, GFP_KERNEL); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, kmem); > + > + useraddr = kunit_vm_mmap(test, NULL, 0, PAGE_SIZE, > + PROT_READ | PROT_WRITE | PROT_EXEC, > + MAP_ANONYMOUS | MAP_PRIVATE, 0); > + KUNIT_ASSERT_NE_MSG(test, useraddr, 0, > + "Could not create userspace mm"); > + KUNIT_ASSERT_LT_MSG(test, useraddr, (unsigned long)TASK_SIZE, > + "Failed to allocate user memory"); > + > + OPTIMIZER_HIDE_VAR(size); > + usermem = (char __user *)useraddr; > + > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = copy_from_user(kmem, usermem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = copy_to_user(usermem, kmem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_from_user(kmem, usermem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_to_user(usermem, kmem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_from_user_inatomic(kmem, usermem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_to_user_inatomic(usermem, kmem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = strncpy_from_user(kmem, usermem, size + 1)); > +} > + > static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(kmalloc_oob_right), > KUNIT_CASE(kmalloc_oob_left), > @@ -2028,6 +2066,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(match_all_ptr_tag), > KUNIT_CASE(match_all_mem_tag), > KUNIT_CASE(rust_uaf), > + KUNIT_CASE(copy_user_test_oob), > {} > }; > > diff --git a/mm/kasan/kasan_test_module.c b/mm/kasan/kasan_test_module.c > deleted file mode 100644 > index 27ec22767e42..000000000000 > --- a/mm/kasan/kasan_test_module.c > +++ /dev/null > @@ -1,81 +0,0 @@ > -// SPDX-License-Identifier: GPL-2.0-only > -/* > - * > - * Copyright (c) 2014 Samsung Electronics Co., Ltd. > - * Author: Andrey Ryabinin <a.ryabinin@samsung.com> > - */ > - > -#define pr_fmt(fmt) "kasan: test: " fmt > - > -#include <linux/mman.h> > -#include <linux/module.h> > -#include <linux/printk.h> > -#include <linux/slab.h> > -#include <linux/uaccess.h> > - > -#include "kasan.h" > - > -static noinline void __init copy_user_test(void) > -{ > - char *kmem; > - char __user *usermem; > - size_t size = 128 - KASAN_GRANULE_SIZE; > - int __maybe_unused unused; > - > - kmem = kmalloc(size, GFP_KERNEL); > - if (!kmem) > - return; > - > - usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE, > - PROT_READ | PROT_WRITE | PROT_EXEC, > - MAP_ANONYMOUS | MAP_PRIVATE, 0); > - if (IS_ERR(usermem)) { > - pr_err("Failed to allocate user memory\n"); > - kfree(kmem); > - return; > - } > - > - OPTIMIZER_HIDE_VAR(size); > - > - pr_info("out-of-bounds in copy_from_user()\n"); > - unused = copy_from_user(kmem, usermem, size + 1); > - > - pr_info("out-of-bounds in copy_to_user()\n"); > - unused = copy_to_user(usermem, kmem, size + 1); > - > - pr_info("out-of-bounds in __copy_from_user()\n"); > - unused = __copy_from_user(kmem, usermem, size + 1); > - > - pr_info("out-of-bounds in __copy_to_user()\n"); > - unused = __copy_to_user(usermem, kmem, size + 1); > - > - pr_info("out-of-bounds in __copy_from_user_inatomic()\n"); > - unused = __copy_from_user_inatomic(kmem, usermem, size + 1); > - > - pr_info("out-of-bounds in __copy_to_user_inatomic()\n"); > - unused = __copy_to_user_inatomic(usermem, kmem, size + 1); > - > - pr_info("out-of-bounds in strncpy_from_user()\n"); > - unused = strncpy_from_user(kmem, usermem, size + 1); > - > - vm_munmap((unsigned long)usermem, PAGE_SIZE); > - kfree(kmem); > -} > - > -static int __init kasan_test_module_init(void) > -{ > - /* > - * Temporarily enable multi-shot mode. Otherwise, KASAN would only > - * report the first detected bug and panic the kernel if panic_on_warn > - * is enabled. > - */ > - bool multishot = kasan_save_enable_multi_shot(); > - > - copy_user_test(); > - > - kasan_restore_multi_shot(multishot); > - return -EAGAIN; > -} > - > -module_init(kasan_test_module_init); > -MODULE_LICENSE("GPL"); > -- > 2.34.1 > This has been tested on: - x86_64 with CONFIG_KASAN_GENERIC - arm64 with CONFIG_KASAN_SW_TAGS - arm64 with CONFIG_KASAN_HW_TAGS - arm64 SW_TAGS has 1 failing test which is in the mainline, will try to address it in different patch, not related to changes in this PR: [ 9.480716] # vmalloc_percpu: EXPECTATION FAILED at mm/kasan/kasan_test_c.c:1830 [ 9.480716] Expected (u8)(__u8)((u64)(c_ptr) >> 56) < (u8)0xFF, but [ 9.480716] (u8)(__u8)((u64)(c_ptr) >> 56) == 255 (0xff) [ 9.480716] (u8)0xFF == 255 (0xff) [ 9.481936] # vmalloc_percpu: EXPECTATION FAILED at mm/kasan/kasan_test_c.c:1830 [ 9.481936] Expected (u8)(__u8)((u64)(c_ptr) >> 56) < (u8)0xFF, but [ 9.481936] (u8)(__u8)((u64)(c_ptr) >> 56) == 255 (0xff) [ 9.481936] (u8)0xFF == 255 (0xff) Here is my full console log of arm64-sw.log: https://gist.githubusercontent.com/novitoll/7ab93edca1f7d71925735075e84fc2ec/raw/6ef05758bcc396cd2f5796a5bcb5e41a091224cf/arm64-sw.log - arm64 HW_TAGS has 1 failing test related to new changes and AFAIU, it's known issue related to HW_TAGS: [ 11.167324] # copy_user_test_oob: EXPECTATION FAILED at mm/kasan/kasan_test_c.c:1992 [ 11.167324] KASAN failure expected in "unused = strncpy_from_user(kmem, usermem, size + 1)", but none occurred Here is the console log of arm64-hw.log: https://gist.github.com/novitoll/7ab93edca1f7d71925735075e84fc2ec#file-arm64-hw-log-L11208
On Fri, Oct 11, 2024 at 9:16 AM Sabyrzhan Tasbolatov <snovitoll@gmail.com> wrote: > > Migrate the copy_user_test to the KUnit framework to verify out-of-bound > detection via KASAN reports in copy_from_user(), copy_to_user() and > their static functions. > > This is the last migrated test in kasan_test_module.c, therefore delete > the file. > > In order to detect OOB access in strncpy_from_user(), we need to move > kasan_check_write() to the function beginning to cover > if (can_do_masked_user_access()) {...} branch as well. > > Reported-by: Andrey Konovalov <andreyknvl@gmail.com> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=212205 > Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com> > --- > lib/strncpy_from_user.c | 3 +- > mm/kasan/kasan_test_c.c | 39 +++++++++++++++++ > mm/kasan/kasan_test_module.c | 81 ------------------------------------ > 3 files changed, 41 insertions(+), 82 deletions(-) > delete mode 100644 mm/kasan/kasan_test_module.c > > diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c > index 989a12a67872..55c33e4f3c70 100644 > --- a/lib/strncpy_from_user.c > +++ b/lib/strncpy_from_user.c > @@ -120,6 +120,8 @@ long strncpy_from_user(char *dst, const char __user *src, long count) > if (unlikely(count <= 0)) > return 0; > > + kasan_check_write(dst, count); > + > if (can_do_masked_user_access()) { > long retval; > > @@ -142,7 +144,6 @@ long strncpy_from_user(char *dst, const char __user *src, long count) > if (max > count) > max = count; > > - kasan_check_write(dst, count); > check_object_size(dst, count, false); I think we better put both kasan_check_write and check_object_size into do_strncpy_from_user, as the latter is now (post 2865baf54077) called from two different places. Also, please put this change into a separate commit with a Fixes: 2865baf54077 tag. > if (user_read_access_begin(src, max)) { > retval = do_strncpy_from_user(dst, src, count, max); > diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c > index a181e4780d9d..e71a16d0dfb9 100644 > --- a/mm/kasan/kasan_test_c.c > +++ b/mm/kasan/kasan_test_c.c > @@ -1954,6 +1954,44 @@ static void rust_uaf(struct kunit *test) > KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf()); > } > > +static void copy_user_test_oob(struct kunit *test) > +{ > + char *kmem; > + char __user *usermem; > + unsigned long useraddr; > + size_t size = 128 - KASAN_GRANULE_SIZE; > + int __maybe_unused unused; > + > + kmem = kunit_kmalloc(test, size, GFP_KERNEL); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, kmem); > + > + useraddr = kunit_vm_mmap(test, NULL, 0, PAGE_SIZE, > + PROT_READ | PROT_WRITE | PROT_EXEC, > + MAP_ANONYMOUS | MAP_PRIVATE, 0); > + KUNIT_ASSERT_NE_MSG(test, useraddr, 0, > + "Could not create userspace mm"); > + KUNIT_ASSERT_LT_MSG(test, useraddr, (unsigned long)TASK_SIZE, > + "Failed to allocate user memory"); > + > + OPTIMIZER_HIDE_VAR(size); > + usermem = (char __user *)useraddr; > + > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = copy_from_user(kmem, usermem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = copy_to_user(usermem, kmem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_from_user(kmem, usermem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_to_user(usermem, kmem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_from_user_inatomic(kmem, usermem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = __copy_to_user_inatomic(usermem, kmem, size + 1)); > + KUNIT_EXPECT_KASAN_FAIL(test, > + unused = strncpy_from_user(kmem, usermem, size + 1)); > +} > + > static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(kmalloc_oob_right), > KUNIT_CASE(kmalloc_oob_left), > @@ -2028,6 +2066,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(match_all_ptr_tag), > KUNIT_CASE(match_all_mem_tag), > KUNIT_CASE(rust_uaf), > + KUNIT_CASE(copy_user_test_oob), > {} > }; > > diff --git a/mm/kasan/kasan_test_module.c b/mm/kasan/kasan_test_module.c > deleted file mode 100644 > index 27ec22767e42..000000000000 > --- a/mm/kasan/kasan_test_module.c > +++ /dev/null > @@ -1,81 +0,0 @@ > -// SPDX-License-Identifier: GPL-2.0-only > -/* > - * > - * Copyright (c) 2014 Samsung Electronics Co., Ltd. > - * Author: Andrey Ryabinin <a.ryabinin@samsung.com> > - */ > - > -#define pr_fmt(fmt) "kasan: test: " fmt > - > -#include <linux/mman.h> > -#include <linux/module.h> > -#include <linux/printk.h> > -#include <linux/slab.h> > -#include <linux/uaccess.h> > - > -#include "kasan.h" > - > -static noinline void __init copy_user_test(void) > -{ > - char *kmem; > - char __user *usermem; > - size_t size = 128 - KASAN_GRANULE_SIZE; > - int __maybe_unused unused; > - > - kmem = kmalloc(size, GFP_KERNEL); > - if (!kmem) > - return; > - > - usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE, > - PROT_READ | PROT_WRITE | PROT_EXEC, > - MAP_ANONYMOUS | MAP_PRIVATE, 0); > - if (IS_ERR(usermem)) { > - pr_err("Failed to allocate user memory\n"); > - kfree(kmem); > - return; > - } > - > - OPTIMIZER_HIDE_VAR(size); > - > - pr_info("out-of-bounds in copy_from_user()\n"); > - unused = copy_from_user(kmem, usermem, size + 1); > - > - pr_info("out-of-bounds in copy_to_user()\n"); > - unused = copy_to_user(usermem, kmem, size + 1); > - > - pr_info("out-of-bounds in __copy_from_user()\n"); > - unused = __copy_from_user(kmem, usermem, size + 1); > - > - pr_info("out-of-bounds in __copy_to_user()\n"); > - unused = __copy_to_user(usermem, kmem, size + 1); > - > - pr_info("out-of-bounds in __copy_from_user_inatomic()\n"); > - unused = __copy_from_user_inatomic(kmem, usermem, size + 1); > - > - pr_info("out-of-bounds in __copy_to_user_inatomic()\n"); > - unused = __copy_to_user_inatomic(usermem, kmem, size + 1); > - > - pr_info("out-of-bounds in strncpy_from_user()\n"); > - unused = strncpy_from_user(kmem, usermem, size + 1); > - > - vm_munmap((unsigned long)usermem, PAGE_SIZE); > - kfree(kmem); > -} > - > -static int __init kasan_test_module_init(void) > -{ > - /* > - * Temporarily enable multi-shot mode. Otherwise, KASAN would only > - * report the first detected bug and panic the kernel if panic_on_warn > - * is enabled. > - */ > - bool multishot = kasan_save_enable_multi_shot(); > - > - copy_user_test(); > - > - kasan_restore_multi_shot(multishot); > - return -EAGAIN; > -} > - > -module_init(kasan_test_module_init); > -MODULE_LICENSE("GPL"); Please also remove the corresponding entries from mm/kasan/Makefile and lib/Kconfig.kasan and update Documentation/dev-tools/kasan.rst. > -- > 2.34.1 >
On Fri, Oct 11, 2024 at 11:12 AM Sabyrzhan Tasbolatov <snovitoll@gmail.com> wrote: > > This has been tested on: > - x86_64 with CONFIG_KASAN_GENERIC > - arm64 with CONFIG_KASAN_SW_TAGS > - arm64 with CONFIG_KASAN_HW_TAGS > > - arm64 SW_TAGS has 1 failing test which is in the mainline, > will try to address it in different patch, not related to changes in this PR: > [ 9.480716] # vmalloc_percpu: EXPECTATION FAILED at > mm/kasan/kasan_test_c.c:1830 > [ 9.480716] Expected (u8)(__u8)((u64)(c_ptr) >> 56) < (u8)0xFF, but > [ 9.480716] (u8)(__u8)((u64)(c_ptr) >> 56) == 255 (0xff) > [ 9.480716] (u8)0xFF == 255 (0xff) > [ 9.481936] # vmalloc_percpu: EXPECTATION FAILED at > mm/kasan/kasan_test_c.c:1830 > [ 9.481936] Expected (u8)(__u8)((u64)(c_ptr) >> 56) < (u8)0xFF, but > [ 9.481936] (u8)(__u8)((u64)(c_ptr) >> 56) == 255 (0xff) > [ 9.481936] (u8)0xFF == 255 (0xff) Could you share the kernel config that you use to get this failure? This test works for me with my config... > Here is my full console log of arm64-sw.log: > https://gist.githubusercontent.com/novitoll/7ab93edca1f7d71925735075e84fc2ec/raw/6ef05758bcc396cd2f5796a5bcb5e41a091224cf/arm64-sw.log > > - arm64 HW_TAGS has 1 failing test related to new changes > and AFAIU, it's known issue related to HW_TAGS: > > [ 11.167324] # copy_user_test_oob: EXPECTATION FAILED at > mm/kasan/kasan_test_c.c:1992 > [ 11.167324] KASAN failure expected in "unused = > strncpy_from_user(kmem, usermem, size + 1)", but none occurred > > Here is the console log of arm64-hw.log: > https://gist.github.com/novitoll/7ab93edca1f7d71925735075e84fc2ec#file-arm64-hw-log-L11208 I don't remember seeing this issue before, did you manage to figure out why this happens? Thank you for working on this!
On Sun, Oct 13, 2024 at 3:49 AM Andrey Konovalov <andreyknvl@gmail.com> wrote: > > On Fri, Oct 11, 2024 at 11:12 AM Sabyrzhan Tasbolatov > <snovitoll@gmail.com> wrote: > > > > This has been tested on: > > - x86_64 with CONFIG_KASAN_GENERIC > > - arm64 with CONFIG_KASAN_SW_TAGS > > - arm64 with CONFIG_KASAN_HW_TAGS > > > > - arm64 SW_TAGS has 1 failing test which is in the mainline, > > will try to address it in different patch, not related to changes in this PR: > > [ 9.480716] # vmalloc_percpu: EXPECTATION FAILED at > > mm/kasan/kasan_test_c.c:1830 > > [ 9.480716] Expected (u8)(__u8)((u64)(c_ptr) >> 56) < (u8)0xFF, but > > [ 9.480716] (u8)(__u8)((u64)(c_ptr) >> 56) == 255 (0xff) > > [ 9.480716] (u8)0xFF == 255 (0xff) > > [ 9.481936] # vmalloc_percpu: EXPECTATION FAILED at > > mm/kasan/kasan_test_c.c:1830 > > [ 9.481936] Expected (u8)(__u8)((u64)(c_ptr) >> 56) < (u8)0xFF, but > > [ 9.481936] (u8)(__u8)((u64)(c_ptr) >> 56) == 255 (0xff) > > [ 9.481936] (u8)0xFF == 255 (0xff) > > Could you share the kernel config that you use to get this failure? > This test works for me with my config... > Here is config for arm64 with SW_TAGS: https://gist.githubusercontent.com/novitoll/7ab93edca1f7d71925735075e84fc2ec/raw/7da07ae3c06009ad80dba87a0ba188934e31b8af/config-arm64-sw , config for arm64 with HW_TAGS: https://gist.githubusercontent.com/novitoll/7ab93edca1f7d71925735075e84fc2ec/raw/7da07ae3c06009ad80dba87a0ba188934e31b8af/config-arm64-hw I've built them with defconfig, then chose in menuconfig KASAN, enabled KUnit tests. $ make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip OBJCOPY=llvm-objcopy \ OBJDUMP=llvm-objdump READELF=llvm-readelf HOSTCC=clang HOSTCXX=clang++ \ HOSTAR=llvm-ar HOSTLD=ld.lld ARCH=arm64 defconfig $ clang --version ClangBuiltLinux clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1) Target: x86_64-unknown-linux-gnu Thread model: posix $ qemu-system-aarch64 \ -machine virt,mte=on \ -cpu max \ -smp 2 \ -m 2048 \ -hda $IMAGE \ -kernel $KERNEL/arch/arm64/boot/Image \ -append "console=ttyAMA0 root=/dev/vda debug earlyprintk=serial net.iframes=0 slub_debug=UZ oops=panic panic_on_warn=1 panic=-1 ftrace_dump_on_oops=orig_cpu" \ -net user,hostfwd=tcp::10023-:22 -net nic \ -nographic \ -pidfile vm.pid \ 2>&1 > > Here is my full console log of arm64-sw.log: > > https://gist.githubusercontent.com/novitoll/7ab93edca1f7d71925735075e84fc2ec/raw/6ef05758bcc396cd2f5796a5bcb5e41a091224cf/arm64-sw.log > > > > - arm64 HW_TAGS has 1 failing test related to new changes > > and AFAIU, it's known issue related to HW_TAGS: > > > > [ 11.167324] # copy_user_test_oob: EXPECTATION FAILED at > > mm/kasan/kasan_test_c.c:1992 > > [ 11.167324] KASAN failure expected in "unused = > > strncpy_from_user(kmem, usermem, size + 1)", but none occurred > > > > Here is the console log of arm64-hw.log: > > https://gist.github.com/novitoll/7ab93edca1f7d71925735075e84fc2ec#file-arm64-hw-log-L11208 > > I don't remember seeing this issue before, did you manage to figure > out why this happens? > I haven't figured it out yet. All I've understood that for HW_TAGS, KASAN_GRANULE_SIZE is MTE_GRANULE_SIZE (16), and I've tried to tweak the buffer size in kunit test, where it's 128 - KASAN_GRANULE_SIZE, I've also tried to understand the if branches in: #define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ ... if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \ , haven't made any progress on it. I've faced a similar issue with HW_TAGS in: https://lore.kernel.org/all/20241011035310.2982017-1-snovitoll@gmail.com/ and also see the comment from you (perhaps, not related): https://bugzilla.kernel.org/show_bug.cgi?id=212205#c2 > Thank you for working on this! Thanks, I'll address your comments in another reply.
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index 989a12a67872..55c33e4f3c70 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -120,6 +120,8 @@ long strncpy_from_user(char *dst, const char __user *src, long count) if (unlikely(count <= 0)) return 0; + kasan_check_write(dst, count); + if (can_do_masked_user_access()) { long retval; @@ -142,7 +144,6 @@ long strncpy_from_user(char *dst, const char __user *src, long count) if (max > count) max = count; - kasan_check_write(dst, count); check_object_size(dst, count, false); if (user_read_access_begin(src, max)) { retval = do_strncpy_from_user(dst, src, count, max); diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c index a181e4780d9d..e71a16d0dfb9 100644 --- a/mm/kasan/kasan_test_c.c +++ b/mm/kasan/kasan_test_c.c @@ -1954,6 +1954,44 @@ static void rust_uaf(struct kunit *test) KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf()); } +static void copy_user_test_oob(struct kunit *test) +{ + char *kmem; + char __user *usermem; + unsigned long useraddr; + size_t size = 128 - KASAN_GRANULE_SIZE; + int __maybe_unused unused; + + kmem = kunit_kmalloc(test, size, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, kmem); + + useraddr = kunit_vm_mmap(test, NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + KUNIT_ASSERT_NE_MSG(test, useraddr, 0, + "Could not create userspace mm"); + KUNIT_ASSERT_LT_MSG(test, useraddr, (unsigned long)TASK_SIZE, + "Failed to allocate user memory"); + + OPTIMIZER_HIDE_VAR(size); + usermem = (char __user *)useraddr; + + KUNIT_EXPECT_KASAN_FAIL(test, + unused = copy_from_user(kmem, usermem, size + 1)); + KUNIT_EXPECT_KASAN_FAIL(test, + unused = copy_to_user(usermem, kmem, size + 1)); + KUNIT_EXPECT_KASAN_FAIL(test, + unused = __copy_from_user(kmem, usermem, size + 1)); + KUNIT_EXPECT_KASAN_FAIL(test, + unused = __copy_to_user(usermem, kmem, size + 1)); + KUNIT_EXPECT_KASAN_FAIL(test, + unused = __copy_from_user_inatomic(kmem, usermem, size + 1)); + KUNIT_EXPECT_KASAN_FAIL(test, + unused = __copy_to_user_inatomic(usermem, kmem, size + 1)); + KUNIT_EXPECT_KASAN_FAIL(test, + unused = strncpy_from_user(kmem, usermem, size + 1)); +} + static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kmalloc_oob_right), KUNIT_CASE(kmalloc_oob_left), @@ -2028,6 +2066,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(match_all_ptr_tag), KUNIT_CASE(match_all_mem_tag), KUNIT_CASE(rust_uaf), + KUNIT_CASE(copy_user_test_oob), {} }; diff --git a/mm/kasan/kasan_test_module.c b/mm/kasan/kasan_test_module.c deleted file mode 100644 index 27ec22767e42..000000000000 --- a/mm/kasan/kasan_test_module.c +++ /dev/null @@ -1,81 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-only -/* - * - * Copyright (c) 2014 Samsung Electronics Co., Ltd. - * Author: Andrey Ryabinin <a.ryabinin@samsung.com> - */ - -#define pr_fmt(fmt) "kasan: test: " fmt - -#include <linux/mman.h> -#include <linux/module.h> -#include <linux/printk.h> -#include <linux/slab.h> -#include <linux/uaccess.h> - -#include "kasan.h" - -static noinline void __init copy_user_test(void) -{ - char *kmem; - char __user *usermem; - size_t size = 128 - KASAN_GRANULE_SIZE; - int __maybe_unused unused; - - kmem = kmalloc(size, GFP_KERNEL); - if (!kmem) - return; - - usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_ANONYMOUS | MAP_PRIVATE, 0); - if (IS_ERR(usermem)) { - pr_err("Failed to allocate user memory\n"); - kfree(kmem); - return; - } - - OPTIMIZER_HIDE_VAR(size); - - pr_info("out-of-bounds in copy_from_user()\n"); - unused = copy_from_user(kmem, usermem, size + 1); - - pr_info("out-of-bounds in copy_to_user()\n"); - unused = copy_to_user(usermem, kmem, size + 1); - - pr_info("out-of-bounds in __copy_from_user()\n"); - unused = __copy_from_user(kmem, usermem, size + 1); - - pr_info("out-of-bounds in __copy_to_user()\n"); - unused = __copy_to_user(usermem, kmem, size + 1); - - pr_info("out-of-bounds in __copy_from_user_inatomic()\n"); - unused = __copy_from_user_inatomic(kmem, usermem, size + 1); - - pr_info("out-of-bounds in __copy_to_user_inatomic()\n"); - unused = __copy_to_user_inatomic(usermem, kmem, size + 1); - - pr_info("out-of-bounds in strncpy_from_user()\n"); - unused = strncpy_from_user(kmem, usermem, size + 1); - - vm_munmap((unsigned long)usermem, PAGE_SIZE); - kfree(kmem); -} - -static int __init kasan_test_module_init(void) -{ - /* - * Temporarily enable multi-shot mode. Otherwise, KASAN would only - * report the first detected bug and panic the kernel if panic_on_warn - * is enabled. - */ - bool multishot = kasan_save_enable_multi_shot(); - - copy_user_test(); - - kasan_restore_multi_shot(multishot); - return -EAGAIN; -} - -module_init(kasan_test_module_init); -MODULE_LICENSE("GPL");
Migrate the copy_user_test to the KUnit framework to verify out-of-bound detection via KASAN reports in copy_from_user(), copy_to_user() and their static functions. This is the last migrated test in kasan_test_module.c, therefore delete the file. In order to detect OOB access in strncpy_from_user(), we need to move kasan_check_write() to the function beginning to cover if (can_do_masked_user_access()) {...} branch as well. Reported-by: Andrey Konovalov <andreyknvl@gmail.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=212205 Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com> --- lib/strncpy_from_user.c | 3 +- mm/kasan/kasan_test_c.c | 39 +++++++++++++++++ mm/kasan/kasan_test_module.c | 81 ------------------------------------ 3 files changed, 41 insertions(+), 82 deletions(-) delete mode 100644 mm/kasan/kasan_test_module.c