* [PATCH stable 6.12 6.6 2/2] selftests/bpf: Add simple strscpy() implementation
2026-07-23 7:13 [PATCH stable 6.12 6.6 1/2] tools/testing: add linux/args.h header and fix radix, VMA tests Shung-Hsi Yu
@ 2026-07-23 7:13 ` Shung-Hsi Yu
2026-07-23 10:19 ` [PATCH stable 6.12 6.6 1/2] tools/testing: add linux/args.h header and fix radix, VMA tests Greg KH
1 sibling, 0 replies; 3+ messages in thread
From: Shung-Hsi Yu @ 2026-07-23 7:13 UTC (permalink / raw)
To: stable
Cc: Shung-Hsi Yu, Lorenzo Stoakes, Jann Horn, John Hubbard,
Liam Howlett, Sidhartha Kumar, Vlastimil Babka, Dan Williams,
Peter Zijlstra, Andrew Morton, Ihor Solodrai, Alexei Starovoitov
From: Ihor Solodrai <ihor.solodrai@linux.dev>
commit 63c49efc987afefc6b9bb7de083eb8748e0b1789 upstream.
Replace bpf_strlcpy() in bpf_util.h with a sized_strscpy(), which is a
simplified sized_strscpy() from the kernel (lib/string.c [1]). It:
* takes a count (destination size) parameter
* guarantees NULL-termination
* returns the number of characters copied or -E2BIG
Re-define strscpy macro similar to in-kernel implementation [2]: allow
the count parameter to be optional.
Add #ifdef-s to tools/include/linux/args.h, as they may be defined in
other system headers (for example, __CONCAT in sys/cdefs.h).
Fixup the single existing bpf_strlcpy() call in cgroup_helpers.c
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/string.c?h=v6.19#n113
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/string.h?h=v6.19#n91
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260223190736.649171-2-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 55ffbe8a15b1 ("selftests/bpf: Initialize operation name before use")
Closes: https://lore.kernel.org/stable/al8dSv_OvhwxFCar@u94a
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
Confirmed that BPF selftests successfully builds on 6.12[1] and 6.6[2]
after this patchset is applied.
1: https://github.com/kernel-patches/linux-stable/actions/runs/29986297264
2: https://github.com/kernel-patches/linux-stable/actions/runs/29987147891/
---
tools/include/linux/args.h | 4 ++
tools/testing/selftests/bpf/bpf_util.h | 45 ++++++++++++++------
tools/testing/selftests/bpf/cgroup_helpers.c | 2 +-
3 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/tools/include/linux/args.h b/tools/include/linux/args.h
index 2e8e65d975c7..14b268f2389a 100644
--- a/tools/include/linux/args.h
+++ b/tools/include/linux/args.h
@@ -22,7 +22,11 @@
#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
/* Concatenate two parameters, but allow them to be expanded beforehand. */
+#ifndef __CONCAT
#define __CONCAT(a, b) a ## b
+#endif
+#ifndef CONCATENATE
#define CONCATENATE(a, b) __CONCAT(a, b)
+#endif
#endif /* _LINUX_ARGS_H */
diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h
index feff92219e21..33486c460913 100644
--- a/tools/testing/selftests/bpf/bpf_util.h
+++ b/tools/testing/selftests/bpf/bpf_util.h
@@ -8,6 +8,7 @@
#include <errno.h>
#include <syscall.h>
#include <bpf/libbpf.h> /* libbpf_num_possible_cpus */
+#include <linux/args.h>
static inline unsigned int bpf_num_possible_cpus(void)
{
@@ -21,25 +22,43 @@ static inline unsigned int bpf_num_possible_cpus(void)
return possible_cpus;
}
-/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst
- * is zero-terminated string no matter what (unless sz == 0, in which case
- * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs
- * in what is returned. Given this is internal helper, it's trivial to extend
- * this, when necessary. Use this instead of strncpy inside libbpf source code.
+/*
+ * Simplified strscpy() implementation. The kernel one is in lib/string.c
*/
-static inline void bpf_strlcpy(char *dst, const char *src, size_t sz)
+static inline ssize_t sized_strscpy(char *dest, const char *src, size_t count)
{
- size_t i;
+ long res = 0;
- if (sz == 0)
- return;
+ if (count == 0)
+ return -E2BIG;
- sz--;
- for (i = 0; i < sz && src[i]; i++)
- dst[i] = src[i];
- dst[i] = '\0';
+ while (count > 1) {
+ char c;
+
+ c = src[res];
+ dest[res] = c;
+ if (!c)
+ return res;
+ res++;
+ count--;
+ }
+
+ /* Force NUL-termination. */
+ dest[res] = '\0';
+
+ /* Return E2BIG if the source didn't stop */
+ return src[res] ? -E2BIG : res;
}
+#define __strscpy0(dst, src, ...) \
+ sized_strscpy(dst, src, sizeof(dst))
+#define __strscpy1(dst, src, size) \
+ sized_strscpy(dst, src, size)
+
+#undef strscpy /* Redefine the placeholder from tools/include/linux/string.h */
+#define strscpy(dst, src, ...) \
+ CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
+
#define __bpf_percpu_val_align __attribute__((__aligned__(8)))
#define BPF_DECLARE_PERCPU(type, name) \
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index e4535451322e..23bcf1aca76f 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -85,7 +85,7 @@ static int __enable_controllers(const char *cgroup_path, const char *controllers
enable[len] = 0;
close(fd);
} else {
- bpf_strlcpy(enable, controllers, sizeof(enable));
+ strscpy(enable, controllers);
}
snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
--
2.55.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH stable 6.12 6.6 1/2] tools/testing: add linux/args.h header and fix radix, VMA tests
2026-07-23 7:13 [PATCH stable 6.12 6.6 1/2] tools/testing: add linux/args.h header and fix radix, VMA tests Shung-Hsi Yu
2026-07-23 7:13 ` [PATCH stable 6.12 6.6 2/2] selftests/bpf: Add simple strscpy() implementation Shung-Hsi Yu
@ 2026-07-23 10:19 ` Greg KH
1 sibling, 0 replies; 3+ messages in thread
From: Greg KH @ 2026-07-23 10:19 UTC (permalink / raw)
To: Shung-Hsi Yu
Cc: stable, Lorenzo Stoakes, Jann Horn, John Hubbard, Liam Howlett,
Sidhartha Kumar, Vlastimil Babka, Dan Williams, Peter Zijlstra,
Andrew Morton
On Thu, Jul 23, 2026 at 03:13:31PM +0800, Shung-Hsi Yu wrote:
> From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>
> commit 9a6a6a3191574a01dcf7a7d9385246d7bc8736bc upstream.
>
> Commit 857d18f23ab1 ("cleanup: Introduce ACQUIRE() and ACQUIRE_ERR() for
> conditional locks") accidentally broke the radix tree, VMA userland tests
> by including linux/args.h which is not present in the tools/include
> directory.
>
> This patch copies this over and adds an #ifdef block to avoid duplicate
> __CONCAT declaration in conflict with system headers when we ultimately
> include this.
>
> Link: https://lkml.kernel.org/r/20250811052654.33286-1-lorenzo.stoakes@oracle.com
> Fixes: 857d18f23ab1 ("cleanup: Introduce ACQUIRE() and ACQUIRE_ERR() for conditional locks")
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: Jann Horn <jannh@google.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Liam Howlett <liam.howlett@oracle.com>
> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Stable-dep-of: 63c49efc987a ("selftests/bpf: Add simple strscpy() implementation")
> Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
> ---
> tools/include/linux/args.h | 28 ++++++++++++++++++++++++++++
> tools/testing/shared/linux/idr.h | 4 ++++
> 2 files changed, 32 insertions(+)
> create mode 100644 tools/include/linux/args.h
>
> diff --git a/tools/include/linux/args.h b/tools/include/linux/args.h
> new file mode 100644
> index 000000000000..2e8e65d975c7
> --- /dev/null
> +++ b/tools/include/linux/args.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef _LINUX_ARGS_H
> +#define _LINUX_ARGS_H
> +
> +/*
> + * How do these macros work?
> + *
> + * In __COUNT_ARGS() _0 to _12 are just placeholders from the start
> + * in order to make sure _n is positioned over the correct number
> + * from 12 to 0 (depending on X, which is a variadic argument list).
> + * They serve no purpose other than occupying a position. Since each
> + * macro parameter must have a distinct identifier, those identifiers
> + * are as good as any.
> + *
> + * In COUNT_ARGS() we use actual integers, so __COUNT_ARGS() returns
> + * that as _n.
> + */
> +
> +/* This counts to 15. Any more, it will return 16th argument. */
> +#define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _n, X...) _n
> +#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
> +
> +/* Concatenate two parameters, but allow them to be expanded beforehand. */
> +#define __CONCAT(a, b) a ## b
> +#define CONCATENATE(a, b) __CONCAT(a, b)
> +
> +#endif /* _LINUX_ARGS_H */
> diff --git a/tools/testing/shared/linux/idr.h b/tools/testing/shared/linux/idr.h
> index 4e342f2e37cf..676c5564e33f 100644
> --- a/tools/testing/shared/linux/idr.h
> +++ b/tools/testing/shared/linux/idr.h
> @@ -1 +1,5 @@
> +/* Avoid duplicate definitions due to system headers. */
> +#ifdef __CONCAT
> +#undef __CONCAT
> +#endif
> #include "../../../../include/linux/idr.h"
> --
> 2.55.0
>
>
Does not apply to 6.6.y at all :(
^ permalink raw reply [flat|nested] 3+ messages in thread