linux-kernel - [PATCH] binfmt_elf_fdpic: fix AUXV size calculation when ELF

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Message-Id: <20240826032745.3423812-1-jcmvbkbc@gmail.com>
Date: Sun, 25 Aug 2024 20:27:45 -0700
From: Max Filippov <jcmvbkbc@...il.com>
To: Greg Ungerer <gregungerer@...tnet.com.au>,
	linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	Eric Biederman <ebiederm@...ssion.com>,
	Kees Cook <kees@...nel.org>,
	Max Filippov <jcmvbkbc@...il.com>,
	stable@...r.kernel.org
Subject: [PATCH] binfmt_elf_fdpic: fix AUXV size calculation when ELF_HWCAP2 is defined

create_elf_fdpic_tables() does not correctly account the space for the
AUX vector when an architecture has ELF_HWCAP2 defined. Prior to the
commit 10e29251be0e ("binfmt_elf_fdpic: fix /proc/<pid>/auxv") it
resulted in the last entry of the AUX vector being set to zero, but with
that change it results in a kernel BUG.

Fix that by adding one to the number of AUXV entries (nitems) when
ELF_HWCAP2 is defined.

Fixes: 10e29251be0e ("binfmt_elf_fdpic: fix /proc/<pid>/auxv")
Cc: stable@...r.kernel.org
Reported-by: Greg Ungerer <gregungerer@...tnet.com.au>
Closes: https://lore.kernel.org/lkml/5b51975f-6d0b-413c-8b38-39a6a45e8821@westnet.com.au/
Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
---
 fs/binfmt_elf_fdpic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index c11289e1301b..a5cb45cb30c8 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -594,6 +594,9 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
 
 	if (bprm->have_execfd)
 		nitems++;
+#ifdef ELF_HWCAP2
+	nitems++;
+#endif
 
 	csp = sp;
 	sp -= nitems * 2 * sizeof(unsigned long);
-- 
2.39.2