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/romfs/storage.c | 287 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 287 insertions(+) create mode 100644 fs/romfs/storage.c (limited to 'fs/romfs/storage.c') diff --git a/fs/romfs/storage.c b/fs/romfs/storage.c new file mode 100644 index 000000000..b57b3ffcb --- /dev/null +++ b/fs/romfs/storage.c @@ -0,0 +1,287 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* RomFS storage access routines + * + * Copyright © 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include "internal.h" + +#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK) +#error no ROMFS backing store interface configured +#endif + +#ifdef CONFIG_ROMFS_ON_MTD +#define ROMFS_MTD_READ(sb, ...) mtd_read((sb)->s_mtd, ##__VA_ARGS__) + +/* + * read data from an romfs image on an MTD device + */ +static int romfs_mtd_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + size_t rlen; + int ret; + + ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf); + return (ret < 0 || rlen != buflen) ? -EIO : 0; +} + +/* + * determine the length of a string in a romfs image on an MTD device + */ +static ssize_t romfs_mtd_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen) +{ + ssize_t n = 0; + size_t segment; + u_char buf[16], *p; + size_t len; + int ret; + + /* scan the string up to 16 bytes at a time */ + while (maxlen > 0) { + segment = min_t(size_t, maxlen, 16); + ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); + if (ret < 0) + return ret; + p = memchr(buf, 0, len); + if (p) + return n + (p - buf); + maxlen -= len; + pos += len; + n += len; + } + + return n; +} + +/* + * compare a string to one in a romfs image on MTD + * - return 1 if matched, 0 if differ, -ve if error + */ +static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + u_char buf[17]; + size_t len, segment; + int ret; + + /* scan the string up to 16 bytes at a time, and attempt to grab the + * trailing NUL whilst we're at it */ + buf[0] = 0xff; + + while (size > 0) { + segment = min_t(size_t, size + 1, 17); + ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); + if (ret < 0) + return ret; + len--; + if (memcmp(buf, str, len) != 0) + return 0; + buf[0] = buf[len]; + size -= len; + pos += len; + str += len; + } + + /* check the trailing NUL was */ + if (buf[0]) + return 0; + + return 1; +} +#endif /* CONFIG_ROMFS_ON_MTD */ + +#ifdef CONFIG_ROMFS_ON_BLOCK +/* + * read data from an romfs image on a block device + */ +static int romfs_blk_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + struct buffer_head *bh; + unsigned long offset; + size_t segment; + + /* copy the string up to blocksize bytes at a time */ + while (buflen > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, buflen, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + memcpy(buf, bh->b_data + offset, segment); + brelse(bh); + buf += segment; + buflen -= segment; + pos += segment; + } + + return 0; +} + +/* + * determine the length of a string in romfs on a block device + */ +static ssize_t romfs_blk_strnlen(struct super_block *sb, + unsigned long pos, size_t limit) +{ + struct buffer_head *bh; + unsigned long offset; + ssize_t n = 0; + size_t segment; + u_char *buf, *p; + + /* scan the string up to blocksize bytes at a time */ + while (limit > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, limit, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + buf = bh->b_data + offset; + p = memchr(buf, 0, segment); + brelse(bh); + if (p) + return n + (p - buf); + limit -= segment; + pos += segment; + n += segment; + } + + return n; +} + +/* + * compare a string to one in a romfs image on a block device + * - return 1 if matched, 0 if differ, -ve if error + */ +static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + struct buffer_head *bh; + unsigned long offset; + size_t segment; + bool matched, terminated = false; + + /* compare string up to a block at a time */ + while (size > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, size, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + matched = (memcmp(bh->b_data + offset, str, segment) == 0); + + size -= segment; + pos += segment; + str += segment; + if (matched && size == 0 && offset + segment < ROMBSIZE) { + if (!bh->b_data[offset + segment]) + terminated = true; + else + matched = false; + } + brelse(bh); + if (!matched) + return 0; + } + + if (!terminated) { + /* the terminating NUL must be on the first byte of the next + * block */ + BUG_ON((pos & (ROMBSIZE - 1)) != 0); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + matched = !bh->b_data[0]; + brelse(bh); + if (!matched) + return 0; + } + + return 1; +} +#endif /* CONFIG_ROMFS_ON_BLOCK */ + +/* + * read data from the romfs image + */ +int romfs_dev_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit || buflen > limit - pos) + return -EIO; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_read(sb, pos, buf, buflen); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_read(sb, pos, buf, buflen); +#endif + return -EIO; +} + +/* + * determine the length of a string in romfs + */ +ssize_t romfs_dev_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (maxlen > limit - pos) + maxlen = limit - pos; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_strnlen(sb, pos, maxlen); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_strnlen(sb, pos, maxlen); +#endif + return -EIO; +} + +/* + * compare a string to one in romfs + * - the string to be compared to, str, may not be NUL-terminated; instead the + * string is of the specified size + * - return 1 if matched, 0 if differ, -ve if error + */ +int romfs_dev_strcmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (size > ROMFS_MAXFN) + return -ENAMETOOLONG; + if (size + 1 > limit - pos) + return -EIO; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_strcmp(sb, pos, str, size); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_strcmp(sb, pos, str, size); +#endif + return -EIO; +} -- cgit v1.3.1