Commit 4e6e8c2b757f ("binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4") added
support for AT_HWCAP3 and AT_HWCAP4, but it missed updating the AUX
vector size calculation in create_elf_fdpic_tables() and
AT_VECTOR_SIZE_BASE in include/linux/auxvec.h.

Similar to the fix for ELF_HWCAP2 in commit c6a09e342f8e
("binfmt_elf_fdpic: fix AUXV size calculation when ELF_HWCAP2 is defined"),
this omission leads to a mismatch between the reserved space and the
actual number of AUX entries, eventually triggering a kernel BUG_ON(csp != sp).

Fix this by incrementing nitems when ELF_HWCAP3 or ELF_HWCAP4 are defined
and updating AT_VECTOR_SIZE_BASE.

Cc: Mark Brown <broonie@kernel.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Fixes: 4e6e8c2b757f ("binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4")
Signed-off-by: Andrei Vagin <avagin@google.com>
---
 fs/binfmt_elf_fdpic.c  | 6 ++++++
 include/linux/auxvec.h | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 48fd2de3bca0..a3d4e6973b29 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -595,6 +595,12 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
 #ifdef ELF_HWCAP2
 	nitems++;
 #endif
+#ifdef ELF_HWCAP3
+	nitems++;
+#endif
+#ifdef ELF_HWCAP4
+	nitems++;
+#endif
 
 	csp = sp;
 	sp -= nitems * 2 * sizeof(unsigned long);
diff --git a/include/linux/auxvec.h b/include/linux/auxvec.h
index 407f7005e6d6..8bcb9b726262 100644
--- a/include/linux/auxvec.h
+++ b/include/linux/auxvec.h
@@ -4,6 +4,6 @@
 
 #include <uapi/linux/auxvec.h>
 
-#define AT_VECTOR_SIZE_BASE 22 /* NEW_AUX_ENT entries in auxiliary table */
+#define AT_VECTOR_SIZE_BASE 24 /* NEW_AUX_ENT entries in auxiliary table */
   /* number of "#define AT_.*" above, minus {AT_NULL, AT_IGNORE, AT_NOTELF} */
 #endif /* _LINUX_AUXVEC_H */
-- 
2.52.0.351.gbe84eed79e-goog

On Thu, Jan 08, 2026 at 05:07:46AM +0000, Andrei Vagin <avagin@google.com> wrote:
> Commit 4e6e8c2b757f ("binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4") added
> support for AT_HWCAP3 and AT_HWCAP4, but it missed updating the AUX
> vector size calculation in create_elf_fdpic_tables() and
> AT_VECTOR_SIZE_BASE in include/linux/auxvec.h.
> 
> Similar to the fix for ELF_HWCAP2 in commit c6a09e342f8e
> ("binfmt_elf_fdpic: fix AUXV size calculation when ELF_HWCAP2 is defined"),
> this omission leads to a mismatch between the reserved space and the
> actual number of AUX entries, eventually triggering a kernel BUG_ON(csp != sp).
> 
> Fix this by incrementing nitems when ELF_HWCAP3 or ELF_HWCAP4 are defined
> and updating AT_VECTOR_SIZE_BASE.
> 
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Max Filippov <jcmvbkbc@gmail.com>
> Fixes: 4e6e8c2b757f ("binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4")
> Signed-off-by: Andrei Vagin <avagin@google.com>
> ---
>  fs/binfmt_elf_fdpic.c  | 6 ++++++
>  include/linux/auxvec.h | 2 +-
>  2 files changed, 7 insertions(+), 1 deletion(-)

Good catch.
Reviewed-by: Michal Koutný <mkoutny@suse.com>

On Thu, Jan 08, 2026 at 05:07:46AM +0000, Andrei Vagin wrote:
> Commit 4e6e8c2b757f ("binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4") added
> support for AT_HWCAP3 and AT_HWCAP4, but it missed updating the AUX
> vector size calculation in create_elf_fdpic_tables() and
> AT_VECTOR_SIZE_BASE in include/linux/auxvec.h.
> 
> Similar to the fix for ELF_HWCAP2 in commit c6a09e342f8e
> ("binfmt_elf_fdpic: fix AUXV size calculation when ELF_HWCAP2 is defined"),
> this omission leads to a mismatch between the reserved space and the
> actual number of AUX entries, eventually triggering a kernel BUG_ON(csp != sp).

Sorry, missed fdpic here:

Reviewed-by: Mark Brown <broonie@kernel.org>