The patch titled Subject: nilfs2: protect references to superblock parameters exposed in sysfs has been added to the -mm mm-hotfixes-unstable branch. Its filename is nilfs2-protect-references-to-superblock-parameters-exposed-in-sysfs.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Ryusuke Konishi konishi.ryusuke@gmail.com Subject: nilfs2: protect references to superblock parameters exposed in sysfs Date: Sun, 11 Aug 2024 19:03:20 +0900

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 ---

fs/nilfs2/sysfs.c | 43 +++++++++++++++++++++++++++++++++---------- 1 file changed, 33 insertions(+), 10 deletions(-)

--- a/fs/nilfs2/sysfs.c~nilfs2-protect-references-to-superblock-parameters-exposed-in-sysfs +++ a/fs/nilfs2/sysfs.c @@ -836,9 +836,15 @@ ssize_t nilfs_dev_revision_show(struct n 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); } @@ -856,8 +862,13 @@ ssize_t nilfs_dev_device_size_show(struc 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); } @@ -879,9 +890,15 @@ ssize_t nilfs_dev_uuid_show(struct nilfs 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 = sysfs_emit(buf, "%pUb\n", raw_sb->s_uuid); + up_read(&nilfs->ns_sem);

- return sysfs_emit(buf, "%pUb\n", sbp[0]->s_uuid); + return len; }

static @@ -889,10 +906,16 @@ ssize_t nilfs_dev_volume_name_show(struc 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[] = _

Patches currently in -mm which might be from konishi.ryusuke@gmail.com are

nilfs2-protect-references-to-superblock-parameters-exposed-in-sysfs.patch