kernel.git/fs/exfat/dir.c, branch linux-6.5.y

vfs: get rid of old '->iterate' directory operation

2023-08-06T13:08:35Z

All users now just use '->iterate_shared()', which only takes the directory inode lock for reading. Filesystems that never got convered to shared mode now instead use a wrapper that drops the lock, re-takes it in write mode, calls the old function, and then downgrades the lock back to read mode. This way the VFS layer and other callers no longer need to care about filesystems that never got converted to the modern era. The filesystems that use the new wrapper are ceph, coda, exfat, jfs, ntfs, ocfs2, overlayfs, and vboxsf. Honestly, several of them look like they really could just iterate their directories in shared mode and skip the wrapper entirely, but the point of this change is to not change semantics or fix filesystems that haven't been fixed in the last 7+ years, but to finally get rid of the dual iterators. Signed-off-by: Linus Torvalds Signed-off-by: Christian Brauner

exfat: release s_lock before calling dir_emit()

2023-07-14T23:34:19Z

There is a potential deadlock reported by syzbot as below: ====================================================== WARNING: possible circular locking dependency detected 6.4.0-next-20230707-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor330/5073 is trying to acquire lock: ffff8880218527a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:151 [inline] ffff8880218527a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5293 [inline] ffff8880218527a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x369/0x510 mm/memory.c:5344 but task is already holding lock: ffff888019f760e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_iterate+0x117/0xb50 fs/exfat/dir.c:232 which lock already depends on the new lock. Chain exists of: &mm->mmap_lock --> mapping.invalidate_lock#3 --> &sbi->s_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sbi->s_lock); lock(mapping.invalidate_lock#3); lock(&sbi->s_lock); rlock(&mm->mmap_lock); Let's try to avoid above potential deadlock condition by moving dir_emit*() out of sbi->s_lock coverage. Fixes: ca06197382bd ("exfat: add directory operations") Cc: stable@vger.kernel.org #v5.7+ Reported-by: syzbot+1741a5d9b79989c10bdc@syzkaller.appspotmail.com Link: https://lore.kernel.org/lkml/00000000000078ee7e060066270b@google.com/T/#u Tested-by: syzbot+1741a5d9b79989c10bdc@syzkaller.appspotmail.com Signed-off-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: check if filename entries exceeds max filename length

2023-07-13T13:02:25Z

exfat_extract_uni_name copies characters from a given file name entry into the 'uniname' variable. This variable is actually defined on the stack of the exfat_readdir() function. According to the definition of the 'exfat_uni_name' type, the file name should be limited 255 characters (+ null teminator space), but the exfat_get_uniname_from_ext_entry() function can write more characters because there is no check if filename entries exceeds max filename length. This patch add the check not to copy filename characters when exceeding max filename length. Cc: stable@vger.kernel.org Cc: Yuezhang Mo Reported-by: Maxim Suhanov Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: handle unreconized benign secondary entries

2023-02-27T12:14:46Z

Sony PXW-Z280 camera add vendor allocation entries to directory of pictures. Currently, linux exfat does not support it and the file is not visible. This patch handle vendor extension and allocation entries as unreconized benign secondary entries. As described in the specification, it is recognized but ignored, and when deleting directory entry set, the associated clusters allocation are removed as well as benign secondary directory entries. Reported-by: Barócsi Dénes Reviewed-by: Sungjong Seo Reviewed-by: Yuezhang Mo Signed-off-by: Namjae Jeon

exfat: fix reporting fs error when reading dir beyond EOF

2023-02-27T12:14:45Z

Since seekdir() does not check whether the position is valid, the position may exceed the size of the directory. We found that for a directory with discontinuous clusters, if the position exceeds the size of the directory and the excess size is greater than or equal to the cluster size, exfat_readdir() will return -EIO, causing a file system error and making the file system unavailable. Reproduce this bug by: seekdir(dir, dir_size + cluster_size); dirent = readdir(dir); The following log will be printed if mount with 'errors=remount-ro'. [11166.712896] exFAT-fs (sdb1): error, invalid access to FAT (entry 0xffffffff) [11166.712905] exFAT-fs (sdb1): Filesystem has been set read-only Fixes: 1e5654de0f51 ("exfat: handle wrong stream entry size in exfat_readdir()") Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: fix unexpected EOF while reading dir

2023-02-27T12:14:44Z

If the position is not aligned with the dentry size, the return value of readdir() will be NULL and errno is 0, which means the end of the directory stream is reached. If the position is aligned with dentry size, but there is no file or directory at the position, exfat_readdir() will continue to get dentry from the next dentry. So the dentry gotten by readdir() may not be at the position. After this commit, if the position is not aligned with the dentry size, round the position up to the dentry size and continue to get the dentry. Fixes: ca06197382bd ("exfat: add directory operations") Cc: stable@vger.kernel.org # v5.7+ Reported-by: Wang Yugui Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: reuse exfat_find_location() to simplify exfat_get_dentry_set()

2022-12-13T11:17:16Z

In exfat_get_dentry_set(), part of the code is the same as exfat_find_location(), reuse exfat_find_location() to simplify exfat_get_dentry_set(). Code refinement, no functional changes. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: remove unnecessary arguments from exfat_find_dir_entry()

2022-12-12T02:02:50Z

This commit removes argument 'num_entries' and 'type' from exfat_find_dir_entry(). Code refinement, no functional changes. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: remove call ilog2() from exfat_readdir()

2022-12-12T02:02:50Z

There is no need to call ilog2() for the conversions between cluster and dentry in exfat_readdir(), because these conversions can be replaced with EXFAT_DEN_TO_CLU()/EXFAT_CLU_TO_DEN(). Code refinement, no functional changes. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon

exfat: replace magic numbers with Macros

2022-12-12T02:02:50Z

Code refinement, no functional changes. Signed-off-by: Yuezhang Mo Reviewed-by: Andy Wu Reviewed-by: Aoyama Wataru Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon