This is a note to let you know that I've just added the patch titled
nilfs2: protect references to superblock parameters exposed in sysfs
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nilfs2-protect-references-to-superblock-parameters-e.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit fbe51150ea8a04e7c87a6dac186ab641b3331da8
Author: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Date: Sun Aug 11 19:03:20 2024 +0900
nilfs2: protect references to superblock parameters exposed in sysfs
[ Upstream commit 683408258917541bdb294cd717c210a04381931e ]
The superblock buffers of nilfs2 can not only be overwritten at runtime
for modifications/repairs, but they are also regularly swapped, replaced
during resizing, and even abandoned when degrading to one side due to
backing device issues. So, accessing them requires mutual exclusion using
the reader/writer semaphore "nilfs->ns_sem".
Some sysfs attribute show methods read this superblock buffer without the
necessary mutual exclusion, which can cause problems with pointer
dereferencing and memory access, so fix it.
Link: https://lkml.kernel.org/r/20240811100320.9913-1-konishi.ryusuke@xxxxxxxxx
Fixes: da7141fb78db ("nilfs2: add /sys/fs/nilfs2/<device> group")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 63ab8f9e6db3..64ea44be0a64 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -843,9 +843,15 @@ ssize_t nilfs_dev_revision_show(struct nilfs_dev_attr *attr,
struct the_nilfs *nilfs,
char *buf)
{
- struct nilfs_super_block **sbp = nilfs->ns_sbp;
- u32 major = le32_to_cpu(sbp[0]->s_rev_level);
- u16 minor = le16_to_cpu(sbp[0]->s_minor_rev_level);
+ struct nilfs_super_block *raw_sb;
+ u32 major;
+ u16 minor;
+
+ down_read(&nilfs->ns_sem);
+ raw_sb = nilfs->ns_sbp[0];
+ major = le32_to_cpu(raw_sb->s_rev_level);
+ minor = le16_to_cpu(raw_sb->s_minor_rev_level);
+ up_read(&nilfs->ns_sem);
return sysfs_emit(buf, "%d.%d\n", major, minor);
}
@@ -863,8 +869,13 @@ ssize_t nilfs_dev_device_size_show(struct nilfs_dev_attr *attr,
struct the_nilfs *nilfs,
char *buf)
{
- struct nilfs_super_block **sbp = nilfs->ns_sbp;
- u64 dev_size = le64_to_cpu(sbp[0]->s_dev_size);
+ struct nilfs_super_block *raw_sb;
+ u64 dev_size;
+
+ down_read(&nilfs->ns_sem);
+ raw_sb = nilfs->ns_sbp[0];
+ dev_size = le64_to_cpu(raw_sb->s_dev_size);
+ up_read(&nilfs->ns_sem);
return sysfs_emit(buf, "%llu\n", dev_size);
}
@@ -886,9 +897,15 @@ ssize_t nilfs_dev_uuid_show(struct nilfs_dev_attr *attr,
struct the_nilfs *nilfs,
char *buf)
{
- struct nilfs_super_block **sbp = nilfs->ns_sbp;
+ struct nilfs_super_block *raw_sb;
+ ssize_t len;
- return sysfs_emit(buf, "%pUb\n", sbp[0]->s_uuid);
+ down_read(&nilfs->ns_sem);
+ raw_sb = nilfs->ns_sbp[0];
+ len = sysfs_emit(buf, "%pUb\n", raw_sb->s_uuid);
+ up_read(&nilfs->ns_sem);
+
+ return len;
}
static
@@ -896,10 +913,16 @@ ssize_t nilfs_dev_volume_name_show(struct nilfs_dev_attr *attr,
struct the_nilfs *nilfs,
char *buf)
{
- struct nilfs_super_block **sbp = nilfs->ns_sbp;
+ struct nilfs_super_block *raw_sb;
+ ssize_t len;
+
+ down_read(&nilfs->ns_sem);
+ raw_sb = nilfs->ns_sbp[0];
+ len = scnprintf(buf, sizeof(raw_sb->s_volume_name), "%s\n",
+ raw_sb->s_volume_name);
+ up_read(&nilfs->ns_sem);
- return scnprintf(buf, sizeof(sbp[0]->s_volume_name), "%s\n",
- sbp[0]->s_volume_name);
+ return len;
}
static const char dev_readme_str[] =
