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init/main: read bootconfig header with get_unaligned_le32()

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get_boot_config_from_initrd() scans up to 3 bytes before initrd_end to
handle GRUB 4-byte alignment.  As a result, the bootconfig header
immediately preceding the magic may be unaligned.

Read the size and checksum fields with get_unaligned_le32() instead of
casting to u32 * and using le32_to_cpu(), avoiding potential unaligned
access and silencing sparse "cast to restricted __le32" warnings.

Sparse warnings (gcc + C=1):
  init/main.c:292:16: warning: cast to restricted __le32
  init/main.c:293:16: warning: cast to restricted __le32

No functional change intended.

Link: https://lkml.kernel.org/r/20260113101532.1630770-1-sun.jian.kdev@gmail.com
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sun Jian 2026-01-13 18:15:32 +08:00 • committed by Andrew Morton
parent a906f3ae44
commit 499f86de4f
1 changed files with 5 additions and 4 deletions
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9
init/main.c
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@ -104,6 +104,7 @@
#include <linux/pidfs.h>
#include <linux/ptdump.h>
#include <linux/time_namespace.h>
#include <linux/unaligned.h>
#include <net/net_namespace.h>
#include <asm/io.h>
@ -270,7 +271,7 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
{
u32 size, csum;
char *data;
u32 *hdr;
u8 *hdr;
int i;
if (!initrd_end)
@ -289,9 +290,9 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
return NULL;
found:
hdr = (u32 *)(data - 8);
size = le32_to_cpu(hdr[0]);
csum = le32_to_cpu(hdr[1]);
hdr = (u8 *)(data - 8);
size = get_unaligned_le32(hdr);
csum = get_unaligned_le32(hdr + 4);
data = ((void *)hdr) - size;
if ((unsigned long)data < initrd_start) {