4.19-stable review patch. If anyone has any objections, please let me know.
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From: Ryusuke Konishi konishi.ryusuke@gmail.com
[ 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@gmail.com Fixes: da7141fb78db ("nilfs2: add /sys/fs/nilfs2/<device> group") Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nilfs2/sysfs.c | 43 +++++++++++++++++++++++++++++++++---------- 1 file changed, 33 insertions(+), 10 deletions(-)
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[] =