From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- fs/squashfs/dir.c | 225 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 225 insertions(+) create mode 100644 fs/squashfs/dir.c (limited to 'fs/squashfs/dir.c') diff --git a/fs/squashfs/dir.c b/fs/squashfs/dir.c new file mode 100644 index 000000000..cd3598bd0 --- /dev/null +++ b/fs/squashfs/dir.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Squashfs - a compressed read only filesystem for Linux + * + * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 + * Phillip Lougher + * + * dir.c + */ + +/* + * This file implements code to read directories from disk. + * + * See namei.c for a description of directory organisation on disk. + */ + +#include +#include +#include +#include + +#include "squashfs_fs.h" +#include "squashfs_fs_sb.h" +#include "squashfs_fs_i.h" +#include "squashfs.h" + +static const unsigned char squashfs_filetype_table[] = { + DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK +}; + +/* + * Lookup offset (f_pos) in the directory index, returning the + * metadata block containing it. + * + * If we get an error reading the index then return the part of the index + * (if any) we have managed to read - the index isn't essential, just + * quicker. + */ +static int get_dir_index_using_offset(struct super_block *sb, + u64 *next_block, int *next_offset, u64 index_start, int index_offset, + int i_count, u64 f_pos) +{ + struct squashfs_sb_info *msblk = sb->s_fs_info; + int err, i, index, length = 0; + unsigned int size; + struct squashfs_dir_index dir_index; + + TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n", + i_count, f_pos); + + /* + * Translate from external f_pos to the internal f_pos. This + * is offset by 3 because we invent "." and ".." entries which are + * not actually stored in the directory. + */ + if (f_pos <= 3) + return f_pos; + f_pos -= 3; + + for (i = 0; i < i_count; i++) { + err = squashfs_read_metadata(sb, &dir_index, &index_start, + &index_offset, sizeof(dir_index)); + if (err < 0) + break; + + index = le32_to_cpu(dir_index.index); + if (index > f_pos) + /* + * Found the index we're looking for. + */ + break; + + size = le32_to_cpu(dir_index.size) + 1; + + /* size should never be larger than SQUASHFS_NAME_LEN */ + if (size > SQUASHFS_NAME_LEN) + break; + + err = squashfs_read_metadata(sb, NULL, &index_start, + &index_offset, size); + if (err < 0) + break; + + length = index; + *next_block = le32_to_cpu(dir_index.start_block) + + msblk->directory_table; + } + + *next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE; + + /* + * Translate back from internal f_pos to external f_pos. + */ + return length + 3; +} + + +static int squashfs_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; + u64 block = squashfs_i(inode)->start + msblk->directory_table; + int offset = squashfs_i(inode)->offset, length, err; + unsigned int inode_number, dir_count, size, type; + struct squashfs_dir_header dirh; + struct squashfs_dir_entry *dire; + + TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset); + + dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL); + if (dire == NULL) { + ERROR("Failed to allocate squashfs_dir_entry\n"); + goto finish; + } + + /* + * Return "." and ".." entries as the first two filenames in the + * directory. To maximise compression these two entries are not + * stored in the directory, and so we invent them here. + * + * It also means that the external f_pos is offset by 3 from the + * on-disk directory f_pos. + */ + while (ctx->pos < 3) { + char *name; + int i_ino; + + if (ctx->pos == 0) { + name = "."; + size = 1; + i_ino = inode->i_ino; + } else { + name = ".."; + size = 2; + i_ino = squashfs_i(inode)->parent; + } + + if (!dir_emit(ctx, name, size, i_ino, + squashfs_filetype_table[1])) + goto finish; + + ctx->pos += size; + } + + length = get_dir_index_using_offset(inode->i_sb, &block, &offset, + squashfs_i(inode)->dir_idx_start, + squashfs_i(inode)->dir_idx_offset, + squashfs_i(inode)->dir_idx_cnt, + ctx->pos); + + while (length < i_size_read(inode)) { + /* + * Read directory header + */ + err = squashfs_read_metadata(inode->i_sb, &dirh, &block, + &offset, sizeof(dirh)); + if (err < 0) + goto failed_read; + + length += sizeof(dirh); + + dir_count = le32_to_cpu(dirh.count) + 1; + + if (dir_count > SQUASHFS_DIR_COUNT) + goto failed_read; + + while (dir_count--) { + /* + * Read directory entry. + */ + err = squashfs_read_metadata(inode->i_sb, dire, &block, + &offset, sizeof(*dire)); + if (err < 0) + goto failed_read; + + size = le16_to_cpu(dire->size) + 1; + + /* size should never be larger than SQUASHFS_NAME_LEN */ + if (size > SQUASHFS_NAME_LEN) + goto failed_read; + + err = squashfs_read_metadata(inode->i_sb, dire->name, + &block, &offset, size); + if (err < 0) + goto failed_read; + + length += sizeof(*dire) + size; + + if (ctx->pos >= length) + continue; + + dire->name[size] = '\0'; + inode_number = le32_to_cpu(dirh.inode_number) + + ((short) le16_to_cpu(dire->inode_number)); + type = le16_to_cpu(dire->type); + + if (type > SQUASHFS_MAX_DIR_TYPE) + goto failed_read; + + if (!dir_emit(ctx, dire->name, size, + inode_number, + squashfs_filetype_table[type])) + goto finish; + + ctx->pos = length; + } + } + +finish: + kfree(dire); + return 0; + +failed_read: + ERROR("Unable to read directory block [%llx:%x]\n", block, offset); + kfree(dire); + return 0; +} + + +const struct file_operations squashfs_dir_ops = { + .read = generic_read_dir, + .iterate_shared = squashfs_readdir, + .llseek = generic_file_llseek, + .setlease = generic_setlease, +}; -- cgit v1.3.1