+ kexec-avoid-calculating-array-size-twice.patch added to mm-nonmm-unstable branch

+ kexec-avoid-calculating-array-size-twice.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: kexec: avoid calculating array size twice
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     kexec-avoid-calculating-array-size-twice.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kexec-avoid-calculating-array-size-twice.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Simon Horman <horms@kernel.org>
Subject: kexec: avoid calculating array size twice
Date: Thu, 25 May 2023 16:26:25 +0200

Avoid calculating array size twice in kexec_purgatory_setup_sechdrs().
Once using array_size(), and once open-coded.

Flagged by Coccinelle:

  .../kexec_file.c:881:8-25: WARNING: array_size is already used (line 877) to compute the same size

No functional change intended.
Compile tested only.

Link: https://lkml.kernel.org/r/20230525-kexec-array_size-v1-1-8b4bf4f7500a@kernel.org
Signed-off-by: Simon Horman <horms@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/kexec_file.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/kernel/kexec_file.c~kexec-avoid-calculating-array-size-twice
+++ a/kernel/kexec_file.c
@@ -867,6 +867,7 @@ static int kexec_purgatory_setup_sechdrs
 {
 	unsigned long bss_addr;
 	unsigned long offset;
+	size_t sechdrs_size;
 	Elf_Shdr *sechdrs;
 	int i;
 
@@ -874,11 +875,11 @@ static int kexec_purgatory_setup_sechdrs
 	 * The section headers in kexec_purgatory are read-only. In order to
 	 * have them modifiable make a temporary copy.
 	 */
-	sechdrs = vzalloc(array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum));
+	sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
+	sechdrs = vzalloc(sechdrs_size);
 	if (!sechdrs)
 		return -ENOMEM;
-	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
-	       pi->ehdr->e_shnum * sizeof(Elf_Shdr));
+	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
 	pi->sechdrs = sechdrs;
 
 	offset = 0;
_

Patches currently in -mm which might be from horms@kernel.org are

kexec-avoid-calculating-array-size-twice.patch