diff mbox series

[bpf] selftests/bpf: Use -4095 as the bad address for bits iterator

Message ID 20241105043057.3371482-1-houtao@huaweicloud.com (mailing list archive)
State Accepted
Commit 6801cf7890f2ed8fcc14859b47501f8ee7a58ec7
Delegated to: BPF
Headers show
Series [bpf] selftests/bpf: Use -4095 as the bad address for bits iterator | expand

Checks

Context Check Description
bpf/vmtest-bpf-PR success PR summary
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for bpf
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success Errors and warnings before: 2 (+0) this patch: 2 (+0)
netdev/cc_maintainers warning 3 maintainers not CCed: shuah@kernel.org linux-kselftest@vger.kernel.org mykolal@fb.com
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 3 this patch: 3
netdev/checkpatch warning WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-VM_Test-0 success Logs for Lint
bpf/vmtest-bpf-VM_Test-2 success Logs for Unittests
bpf/vmtest-bpf-VM_Test-5 success Logs for aarch64-gcc / build-release
bpf/vmtest-bpf-VM_Test-10 success Logs for aarch64-gcc / veristat
bpf/vmtest-bpf-VM_Test-9 success Logs for aarch64-gcc / test (test_verifier, false, 360) / test_verifier on aarch64 with gcc
bpf/vmtest-bpf-VM_Test-12 success Logs for s390x-gcc / build-release
bpf/vmtest-bpf-VM_Test-11 success Logs for s390x-gcc / build / build for s390x with gcc
bpf/vmtest-bpf-VM_Test-16 success Logs for s390x-gcc / veristat
bpf/vmtest-bpf-VM_Test-17 success Logs for set-matrix
bpf/vmtest-bpf-VM_Test-15 success Logs for s390x-gcc / test (test_verifier, false, 360) / test_verifier on s390x with gcc
bpf/vmtest-bpf-VM_Test-18 success Logs for x86_64-gcc / build / build for x86_64 with gcc
bpf/vmtest-bpf-VM_Test-19 success Logs for x86_64-gcc / build-release
bpf/vmtest-bpf-VM_Test-20 success Logs for x86_64-gcc / test (test_maps, false, 360) / test_maps on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-29 success Logs for x86_64-llvm-17 / test (test_maps, false, 360) / test_maps on x86_64 with llvm-17
bpf/vmtest-bpf-VM_Test-21 success Logs for x86_64-gcc / test (test_progs, false, 360) / test_progs on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-23 success Logs for x86_64-gcc / test (test_progs_no_alu32_parallel, true, 30) / test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-24 success Logs for x86_64-gcc / test (test_progs_parallel, true, 30) / test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-25 success Logs for x86_64-gcc / test (test_verifier, false, 360) / test_verifier on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-26 success Logs for x86_64-gcc / veristat / veristat on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-22 success Logs for x86_64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-VM_Test-27 success Logs for x86_64-llvm-17 / build / build for x86_64 with llvm-17
bpf/vmtest-bpf-VM_Test-28 success Logs for x86_64-llvm-17 / build-release / build for x86_64 with llvm-17-O2
bpf/vmtest-bpf-VM_Test-33 success Logs for x86_64-llvm-17 / veristat
bpf/vmtest-bpf-VM_Test-35 success Logs for x86_64-llvm-18 / build-release / build for x86_64 with llvm-18-O2
bpf/vmtest-bpf-VM_Test-32 success Logs for x86_64-llvm-17 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-17
bpf/vmtest-bpf-VM_Test-34 success Logs for x86_64-llvm-18 / build / build for x86_64 with llvm-18
bpf/vmtest-bpf-VM_Test-36 success Logs for x86_64-llvm-18 / test (test_maps, false, 360) / test_maps on x86_64 with llvm-18
bpf/vmtest-bpf-VM_Test-39 success Logs for x86_64-llvm-18 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-18
bpf/vmtest-bpf-VM_Test-37 success Logs for x86_64-llvm-18 / test (test_progs, false, 360) / test_progs on x86_64 with llvm-18
bpf/vmtest-bpf-VM_Test-38 success Logs for x86_64-llvm-18 / test (test_progs_cpuv4, false, 360) / test_progs_cpuv4 on x86_64 with llvm-18
bpf/vmtest-bpf-VM_Test-41 success Logs for x86_64-llvm-18 / veristat
bpf/vmtest-bpf-VM_Test-40 success Logs for x86_64-llvm-18 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-18
bpf/vmtest-bpf-VM_Test-8 success Logs for aarch64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on aarch64 with gcc
bpf/vmtest-bpf-VM_Test-7 success Logs for aarch64-gcc / test (test_progs, false, 360) / test_progs on aarch64 with gcc
bpf/vmtest-bpf-VM_Test-14 success Logs for s390x-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-VM_Test-30 success Logs for x86_64-llvm-17 / test (test_progs, false, 360) / test_progs on x86_64 with llvm-17
bpf/vmtest-bpf-VM_Test-31 success Logs for x86_64-llvm-17 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-17
bpf/vmtest-bpf-VM_Test-13 success Logs for s390x-gcc / test (test_progs, false, 360) / test_progs on s390x with gcc
bpf/vmtest-bpf-VM_Test-1 success Logs for aarch64-gcc / build-release
bpf/vmtest-bpf-VM_Test-6 success Logs for x86_64-gcc / build-release
bpf/vmtest-bpf-VM_Test-3 success Logs for s390x-gcc / build-release
bpf/vmtest-bpf-VM_Test-4 success Logs for set-matrix

Commit Message

Hou Tao Nov. 5, 2024, 4:30 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

As reported by Byeonguk, the bad_words test in verifier_bits_iter.c
occasionally fails on s390 host. Quoting Ilya's explanation:

  s390 kernel runs in a completely separate address space, there is no
  user/kernel split at TASK_SIZE. The same address may be valid in both
  the kernel and the user address spaces, there is no way to tell by
  looking at it. The config option related to this property is
  ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.

  Also, unfortunately, 0 is a valid address in the s390 kernel address
  space.

Fix the issue by using -4096 as the bad address for bits iterator, as
suggested by Ilya. Verify that bpf_iter_bits_new() returns -EINVAL for
NULL address and -EFAULT for bad address.

Fixes: ebafc1e535db ("selftests/bpf: Add three test cases for bits_iter")
Reported-by: Byeonguk Jeong <jungbu2855@gmail.com>
Closes: https://lore.kernel.org/bpf/ZycSXwjH4UTvx-Cn@ub22/
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 .../selftests/bpf/progs/verifier_bits_iter.c  | 32 ++++++++++++++++---
 1 file changed, 28 insertions(+), 4 deletions(-)

Comments

Ilya Leoshkevich Nov. 5, 2024, 8:18 p.m. UTC | #1 
On Tue, 2024-11-05 at 12:30 +0800, Hou Tao wrote:
> From: Hou Tao <houtao1@huawei.com>
> 
> As reported by Byeonguk, the bad_words test in verifier_bits_iter.c
> occasionally fails on s390 host. Quoting Ilya's explanation:
> 
>   s390 kernel runs in a completely separate address space, there is
> no
>   user/kernel split at TASK_SIZE. The same address may be valid in
> both
>   the kernel and the user address spaces, there is no way to tell by
>   looking at it. The config option related to this property is
>   ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
> 
>   Also, unfortunately, 0 is a valid address in the s390 kernel
> address
>   space.
> 
> Fix the issue by using -4096 as the bad address for bits iterator, as
> suggested by Ilya. Verify that bpf_iter_bits_new() returns -EINVAL
> for
> NULL address and -EFAULT for bad address.

The code uses -4095, which I think is better, since it's the current
value of MAX_ERRNO, therefore, IS_ERR_VALUE() sees it as an error. It's
also not aligned, which may be an additional reason it may not be
dereferenceable on some CPUs.

Other than this discrepancy in the commit message:

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>

> Fixes: ebafc1e535db ("selftests/bpf: Add three test cases for
> bits_iter")
> Reported-by: Byeonguk Jeong <jungbu2855@gmail.com>
> Closes: https://lore.kernel.org/bpf/ZycSXwjH4UTvx-Cn@ub22/
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
>  .../selftests/bpf/progs/verifier_bits_iter.c  | 32 ++++++++++++++++-
> --
>  1 file changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
> b/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
> index 156cc278e2fc..7c881bca9af5 100644
> --- a/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
> +++ b/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
> @@ -57,9 +57,15 @@ __description("null pointer")
>  __success __retval(0)
>  int null_pointer(void)
>  {
> -	int nr = 0;
> +	struct bpf_iter_bits iter;
> +	int err, nr = 0;
>  	int *bit;
>  
> +	err = bpf_iter_bits_new(&iter, NULL, 1);
> +	bpf_iter_bits_destroy(&iter);
> +	if (err != -EINVAL)
> +		return 1;
> +
>  	bpf_for_each(bits, bit, NULL, 1)
>  		nr++;
>  	return nr;
> @@ -194,15 +200,33 @@ __description("bad words")
>  __success __retval(0)
>  int bad_words(void)
>  {
> -	void *bad_addr = (void *)(3UL << 30);
> -	int nr = 0;
> +	void *bad_addr = (void *)-4095;
> +	struct bpf_iter_bits iter;
> +	volatile int nr;
>  	int *bit;
> +	int err;
> +
> +	err = bpf_iter_bits_new(&iter, bad_addr, 1);
> +	bpf_iter_bits_destroy(&iter);
> +	if (err != -EFAULT)
> +		return 1;
>  
> +	nr = 0;
>  	bpf_for_each(bits, bit, bad_addr, 1)
>  		nr++;
> +	if (nr != 0)
> +		return 2;
>  
> +	err = bpf_iter_bits_new(&iter, bad_addr, 4);
> +	bpf_iter_bits_destroy(&iter);
> +	if (err != -EFAULT)
> +		return 3;
> +
> +	nr = 0;
>  	bpf_for_each(bits, bit, bad_addr, 4)
>  		nr++;
> +	if (nr != 0)
> +		return 4;
>  
> -	return nr;
> +	return 0;
>  }
Alexei Starovoitov Nov. 5, 2024, 10:04 p.m. UTC | #2 
On Tue, Nov 5, 2024 at 12:18 PM Ilya Leoshkevich <iii@linux.ibm.com> wrote:
>
> On Tue, 2024-11-05 at 12:30 +0800, Hou Tao wrote:
> > From: Hou Tao <houtao1@huawei.com>
> >
> > As reported by Byeonguk, the bad_words test in verifier_bits_iter.c
> > occasionally fails on s390 host. Quoting Ilya's explanation:
> >
> >   s390 kernel runs in a completely separate address space, there is
> > no
> >   user/kernel split at TASK_SIZE. The same address may be valid in
> > both
> >   the kernel and the user address spaces, there is no way to tell by
> >   looking at it. The config option related to this property is
> >   ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
> >
> >   Also, unfortunately, 0 is a valid address in the s390 kernel
> > address
> >   space.
> >
> > Fix the issue by using -4096 as the bad address for bits iterator, as
> > suggested by Ilya. Verify that bpf_iter_bits_new() returns -EINVAL
> > for
> > NULL address and -EFAULT for bad address.
>
> The code uses -4095, which I think is better, since it's the current
> value of MAX_ERRNO, therefore, IS_ERR_VALUE() sees it as an error. It's
> also not aligned, which may be an additional reason it may not be
> dereferenceable on some CPUs.
>
> Other than this discrepancy in the commit message:
>
> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>

Fixed it up while applying.
patchwork-bot+netdevbpf@kernel.org Nov. 5, 2024, 10:10 p.m. UTC | #3 
Hello:

This patch was applied to bpf/bpf.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Tue,  5 Nov 2024 12:30:57 +0800 you wrote:
> From: Hou Tao <houtao1@huawei.com>
> 
> As reported by Byeonguk, the bad_words test in verifier_bits_iter.c
> occasionally fails on s390 host. Quoting Ilya's explanation:
> 
>   s390 kernel runs in a completely separate address space, there is no
>   user/kernel split at TASK_SIZE. The same address may be valid in both
>   the kernel and the user address spaces, there is no way to tell by
>   looking at it. The config option related to this property is
>   ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
> 
> [...]

Here is the summary with links:
  - [bpf] selftests/bpf: Use -4095 as the bad address for bits iterator
    https://git.kernel.org/bpf/bpf/c/6801cf7890f2

You are awesome, thank you!
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/progs/verifier_bits_iter.c b/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
index 156cc278e2fc..7c881bca9af5 100644
--- a/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
+++ b/tools/testing/selftests/bpf/progs/verifier_bits_iter.c
@@ -57,9 +57,15 @@  __description("null pointer")
 __success __retval(0)
 int null_pointer(void)
 {
-	int nr = 0;
+	struct bpf_iter_bits iter;
+	int err, nr = 0;
 	int *bit;
 
+	err = bpf_iter_bits_new(&iter, NULL, 1);
+	bpf_iter_bits_destroy(&iter);
+	if (err != -EINVAL)
+		return 1;
+
 	bpf_for_each(bits, bit, NULL, 1)
 		nr++;
 	return nr;
@@ -194,15 +200,33 @@  __description("bad words")
 __success __retval(0)
 int bad_words(void)
 {
-	void *bad_addr = (void *)(3UL << 30);
-	int nr = 0;
+	void *bad_addr = (void *)-4095;
+	struct bpf_iter_bits iter;
+	volatile int nr;
 	int *bit;
+	int err;
+
+	err = bpf_iter_bits_new(&iter, bad_addr, 1);
+	bpf_iter_bits_destroy(&iter);
+	if (err != -EFAULT)
+		return 1;
 
+	nr = 0;
 	bpf_for_each(bits, bit, bad_addr, 1)
 		nr++;
+	if (nr != 0)
+		return 2;
 
+	err = bpf_iter_bits_new(&iter, bad_addr, 4);
+	bpf_iter_bits_destroy(&iter);
+	if (err != -EFAULT)
+		return 3;
+
+	nr = 0;
 	bpf_for_each(bits, bit, bad_addr, 4)
 		nr++;
+	if (nr != 0)
+		return 4;
 
-	return nr;
+	return 0;
 }