linux-kernel - [PATCH v2 1/6] ext4: sysfs: print ext4_super

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180711091414.1494843-1-arnd@arndb.de>
Date:   Wed, 11 Jul 2018 11:14:09 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     adilger.kernel@...ger.ca
Cc:     arnd@...db.de, jack@...e.cz, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, sirmy15@...il.com,
        stable@...r.kernel.org, tgnottingham@...il.com, tytso@....edu,
        y2038@...ts.linaro.org
Subject: [PATCH v2 1/6] 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@...r.kernel.org
Fixes: 52c198c6820f ("ext4: add sysfs entry showing whether the fs contains errors")
Reviewed-by: Andreas Dilger <adilger@...ger.ca>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/ext4/sysfs.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

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);
-- 
2.9.0