[PATCH 6.18 195/212] binfmt_elf_fdpic: fix AUXV size calculation for ELF_HWCAP3 and ELF_HWCAP4

Greg Kroah-Hartman
2026-03-23T14:10:20Z

From: Andrei Vagin <avagin@google.com>

[ Upstream commit 4ced4cf5c9d172d91f181df3accdf949d3761aab ]

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 AT_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>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
Fixes: 4e6e8c2b757f ("binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4")
Signed-off-by: Andrei Vagin <avagin@google.com>
Link: https://patch.msgid.link/20260217180108.1420024-2-avagin@google.com
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 48fd2de3bca05..a3d4e6973b299 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 407f7005e6d60..8bcb9b7262628 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 */
--
2.51.0