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@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a4d2aadca184ece182418950d45ba4ffc7b652d2 Mon Sep 17 00:00:00 2001

From: Arnd Bergmann arnd@arndb.de 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@vger.kernel.org Fixes: 52c198c6820f ("ext4: add sysfs entry showing whether the fs contains errors") Reviewed-by: Andreas Dilger adilger@dilger.ca Signed-off-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Theodore Ts'o tytso@mit.edu

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);