The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From a4d2aadca184ece182418950d45ba4ffc7b652d2 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@xxxxxxxx>
Date: Sun, 29 Jul 2018 15:48:00 -0400
Subject: [PATCH] ext4: sysfs: print ext4_super_block fields as little-endian
While working on extended rand for last_error/first_error timestamps,
I noticed that the endianess is wrong; we access the little-endian
fields in struct ext4_super_block as native-endian when we print them.
This adds a special case in ext4_attr_show() and ext4_attr_store()
to byteswap the superblock fields if needed.
In older kernels, this code was part of super.c, it got moved to
sysfs.c in linux-4.4.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 52c198c6820f ("ext4: add sysfs entry showing whether the fs contains errors")
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index f34da0bb8f17..b970a200f20c 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -274,8 +274,12 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
case attr_pointer_ui:
if (!ptr)
return 0;
- return snprintf(buf, PAGE_SIZE, "%u\n",
- *((unsigned int *) ptr));
+ if (a->attr_ptr == ptr_ext4_super_block_offset)
+ return snprintf(buf, PAGE_SIZE, "%u\n",
+ le32_to_cpup(ptr));
+ else
+ return snprintf(buf, PAGE_SIZE, "%u\n",
+ *((unsigned int *) ptr));
case attr_pointer_atomic:
if (!ptr)
return 0;
@@ -308,7 +312,10 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
ret = kstrtoul(skip_spaces(buf), 0, &t);
if (ret)
return ret;
- *((unsigned int *) ptr) = t;
+ if (a->attr_ptr == ptr_ext4_super_block_offset)
+ *((__le32 *) ptr) = cpu_to_le32(t);
+ else
+ *((unsigned int *) ptr) = t;
return len;
case attr_inode_readahead:
return inode_readahead_blks_store(sbi, buf, len);
