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 --- lib/argv_split.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 lib/argv_split.c (limited to 'lib/argv_split.c') diff --git a/lib/argv_split.c b/lib/argv_split.c new file mode 100644 index 000000000..e28db8e3b --- /dev/null +++ b/lib/argv_split.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Helper function for splitting a string into an argv-like array. + */ + +#include +#include +#include +#include +#include + +static int count_argc(const char *str) +{ + int count = 0; + bool was_space; + + for (was_space = true; *str; str++) { + if (isspace(*str)) { + was_space = true; + } else if (was_space) { + was_space = false; + count++; + } + } + + return count; +} + +/** + * argv_free - free an argv + * @argv: the argument vector to be freed + * + * Frees an argv and the strings it points to. + */ +void argv_free(char **argv) +{ + argv--; + kfree(argv[0]); + kfree(argv); +} +EXPORT_SYMBOL(argv_free); + +/** + * argv_split - split a string at whitespace, returning an argv + * @gfp: the GFP mask used to allocate memory + * @str: the string to be split + * @argcp: returned argument count + * + * Returns: an array of pointers to strings which are split out from + * @str. This is performed by strictly splitting on white-space; no + * quote processing is performed. Multiple whitespace characters are + * considered to be a single argument separator. The returned array + * is always NULL-terminated. Returns NULL on memory allocation + * failure. + * + * The source string at `str' may be undergoing concurrent alteration via + * userspace sysctl activity (at least). The argv_split() implementation + * attempts to handle this gracefully by taking a local copy to work on. + */ +char **argv_split(gfp_t gfp, const char *str, int *argcp) +{ + char *argv_str; + bool was_space; + char **argv, **argv_ret; + int argc; + + argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp); + if (!argv_str) + return NULL; + + argc = count_argc(argv_str); + argv = kmalloc_array(argc + 2, sizeof(*argv), gfp); + if (!argv) { + kfree(argv_str); + return NULL; + } + + *argv = argv_str; + argv_ret = ++argv; + for (was_space = true; *argv_str; argv_str++) { + if (isspace(*argv_str)) { + was_space = true; + *argv_str = 0; + } else if (was_space) { + was_space = false; + *argv++ = argv_str; + } + } + *argv = NULL; + + if (argcp) + *argcp = argc; + return argv_ret; +} +EXPORT_SYMBOL(argv_split); -- cgit v1.3.1