From 4310c6b8e75d6a47f7548e5948fbe6318aa4440a Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Mon, 31 Aug 2026 10:58:09 +0300 Subject: thunderbolt: Fix NULL dereference in tb_remove_work() There is a slight race between tb_remove_work() and tb_domain_remove() which leads to dereferencing a NULL tb->root_switch pointer inside tb_free_unplugged_xdomains(): Thread A Thread B tb_remove_work() tb_domain_remove() mutex_lock(&tb->lock) tb_stop() /* doesn't cancel a running callback */ cancel_delayed_work(&tcm->remove_work) ... tb_switch_remove(tb->root_switch) tb->root_switch = NULL mutex_unlock(&tb->lock) mutex_lock(&tb->lock) ... /* without checking ->root_switch */ tb_free_unplugged_xdomains(tb->root_switch) mutex_unlock(&tb->lock) Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains() out of the &tb->lock section and the check for tb->root_switch, in particular. It states: For this reason separate removing the XDomain from the topology data structures (where we need the lock) from unregistering the device from the bus (where remove callbacks of the drivers are being called). tb_free_unplugged_xdomains() belongs to the former group of functions requiring the lock. And it also calls tb_xdomain_remove() which should only be called with &tb->lock held. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Signed-off-by: Mika Westerberg --- tools/lib/subcmd/run-command.c | 358 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 358 insertions(+) create mode 100644 tools/lib/subcmd/run-command.c (limited to 'tools/lib/subcmd/run-command.c') diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c new file mode 100644 index 000000000..bd21b8bfd --- /dev/null +++ b/tools/lib/subcmd/run-command.c @@ -0,0 +1,358 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "subcmd-util.h" +#include "run-command.h" +#include "exec-cmd.h" + +#define STRERR_BUFSIZE 128 + +static inline void close_pair(int fd[2]) +{ + close(fd[0]); + close(fd[1]); +} + +static inline void dup_devnull(int to) +{ + int fd = open("/dev/null", O_RDWR); + dup2(fd, to); + close(fd); +} + +int start_command(struct child_process *cmd) +{ + int need_in, need_out, need_err; + int fdin[2], fdout[2], fderr[2]; + char sbuf[STRERR_BUFSIZE]; + + /* + * In case of errors we must keep the promise to close FDs + * that have been passed in via ->in and ->out. + */ + + need_in = !cmd->no_stdin && cmd->in < 0; + if (need_in) { + if (pipe(fdin) < 0) { + if (cmd->out > 0) + close(cmd->out); + return -ERR_RUN_COMMAND_PIPE; + } + cmd->in = fdin[1]; + } + + need_out = !cmd->no_stdout + && !cmd->stdout_to_stderr + && cmd->out < 0; + if (need_out) { + if (pipe(fdout) < 0) { + if (need_in) + close_pair(fdin); + else if (cmd->in) + close(cmd->in); + return -ERR_RUN_COMMAND_PIPE; + } + cmd->out = fdout[0]; + } + + need_err = !cmd->no_stderr && cmd->err < 0; + if (need_err) { + if (pipe(fderr) < 0) { + if (need_in) + close_pair(fdin); + else if (cmd->in) + close(cmd->in); + if (need_out) + close_pair(fdout); + else if (cmd->out) + close(cmd->out); + return -ERR_RUN_COMMAND_PIPE; + } + cmd->err = fderr[0]; + } + + fflush(NULL); + cmd->pid = fork(); + if (!cmd->pid) { + if (cmd->no_stdin) + dup_devnull(0); + else if (need_in) { + dup2(fdin[0], 0); + close_pair(fdin); + } else if (cmd->in) { + dup2(cmd->in, 0); + close(cmd->in); + } + + if (cmd->no_stderr) + dup_devnull(2); + else if (need_err) { + dup2(fderr[1], 2); + close_pair(fderr); + } + + if (cmd->no_stdout) + dup_devnull(1); + else if (cmd->stdout_to_stderr) + dup2(2, 1); + else if (need_out) { + dup2(fdout[1], 1); + close_pair(fdout); + } else if (cmd->out > 1) { + dup2(cmd->out, 1); + close(cmd->out); + } + + if (cmd->dir && chdir(cmd->dir)) + die("exec %s: cd to %s failed (%s)", cmd->argv[0], + cmd->dir, str_error_r(errno, sbuf, sizeof(sbuf))); + if (cmd->env) { + for (; *cmd->env; cmd->env++) { + if (strchr(*cmd->env, '=')) + putenv((char*)*cmd->env); + else + unsetenv(*cmd->env); + } + } + if (cmd->preexec_cb) + cmd->preexec_cb(); + if (cmd->no_exec_cmd) + exit(cmd->no_exec_cmd(cmd)); + if (cmd->exec_cmd) { + execv_cmd(cmd->argv); + } else { + execvp(cmd->argv[0], (char *const*) cmd->argv); + } + exit(127); + } + + if (cmd->pid < 0) { + int err = errno; + if (need_in) + close_pair(fdin); + else if (cmd->in) + close(cmd->in); + if (need_out) + close_pair(fdout); + else if (cmd->out) + close(cmd->out); + if (need_err) + close_pair(fderr); + return err == ENOENT ? + -ERR_RUN_COMMAND_EXEC : + -ERR_RUN_COMMAND_FORK; + } + + if (need_in) + close(fdin[0]); + else if (cmd->in) + close(cmd->in); + + if (need_out) + close(fdout[1]); + else if (cmd->out) + close(cmd->out); + + if (need_err) + close(fderr[1]); + + return 0; +} + +static int wait_or_whine(struct child_process *cmd, bool block) +{ + bool finished; + int result; + + if (cmd->pid <= 0) { + cmd->finished = 1; + if (cmd->pid < 0 && cmd->finish_result == 0) + cmd->finish_result = -ERR_RUN_COMMAND_FORK; + return cmd->finish_result; + } + + finished = cmd->finished; + result = cmd->finish_result; + + while (!finished) { + int status, code; + pid_t waiting = waitpid(cmd->pid, &status, block ? 0 : WNOHANG); + + if (!block && waiting == 0) + break; + + if (waiting < 0 && errno == EINTR) + continue; + + finished = true; + if (waiting < 0) { + char sbuf[STRERR_BUFSIZE]; + + fprintf(stderr, " Error: waitpid failed (%s)", + str_error_r(errno, sbuf, sizeof(sbuf))); + result = -ERR_RUN_COMMAND_WAITPID; + } else if (waiting != cmd->pid) { + result = -ERR_RUN_COMMAND_WAITPID_WRONG_PID; + } else if (WIFSIGNALED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_SIGNAL; + } else if (!WIFEXITED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_NOEXIT; + } else { + code = WEXITSTATUS(status); + switch (code) { + case 127: + result = -ERR_RUN_COMMAND_EXEC; + break; + case 0: + result = 0; + break; + default: + result = -code; + break; + } + } + } + if (finished) { + cmd->finished = 1; + cmd->finish_result = result; + } + return result; +} + +/* + * Conservative estimate of number of characaters needed to hold an a decoded + * integer, assume each 3 bits needs a character byte and plus a possible sign + * character. + */ +#ifndef is_signed_type +#define is_signed_type(type) (((type)(-1)) < (type)1) +#endif +#define MAX_STRLEN_TYPE(type) (sizeof(type) * 8 / 3 + (is_signed_type(type) ? 1 : 0)) + +int check_if_command_finished(struct child_process *cmd) +{ +#ifdef __linux__ + char filename[6 + MAX_STRLEN_TYPE(typeof(cmd->pid)) + 7 + 1]; + char status_line[256]; + FILE *status_file; +#endif + + if (cmd->finished) + return 1; + if (cmd->pid <= 0) { + cmd->finished = 1; + if (cmd->pid < 0 && cmd->finish_result == 0) + cmd->finish_result = -ERR_RUN_COMMAND_FORK; + return 1; + } + +#ifdef __linux__ + /* + * Check by reading /proc//status as calling waitpid causes + * stdout/stderr to be closed and data lost. + */ + sprintf(filename, "/proc/%u/status", cmd->pid); + status_file = fopen(filename, "r"); + if (status_file == NULL) { + int status; + pid_t waiting; + + /* + * fopen() can fail with ENOENT if the process has been reaped. + * It can also fail with EMFILE/ENFILE if RLIMIT_NOFILE is reached. + * In those cases, use waitpid(..., WNOHANG) to robustly check + * and reap the process if it has exited. + */ + if (errno == ENOENT) + return 1; + + waiting = waitpid(cmd->pid, &status, WNOHANG); + if (waiting == cmd->pid) { + int result; + int code; + + cmd->finished = 1; + if (WIFSIGNALED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_SIGNAL; + } else if (!WIFEXITED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_NOEXIT; + } else { + code = WEXITSTATUS(status); + switch (code) { + case 127: + result = -ERR_RUN_COMMAND_EXEC; + break; + case 0: + result = 0; + break; + default: + result = -code; + break; + } + } + cmd->finish_result = result; + return 1; + } + if (waiting < 0 && (errno == ECHILD || errno == ESRCH)) + return 1; + return 0; + } + while (fgets(status_line, sizeof(status_line), status_file) != NULL) { + char *p; + + if (strncmp(status_line, "State:", 6)) + continue; + + fclose(status_file); + p = status_line + 6; + while (isspace(*p)) + p++; + return *p == 'Z' ? 1 : 0; + } + /* Read failed assume finish_command was called. */ + fclose(status_file); + return 1; +#else + wait_or_whine(cmd, /*block=*/false); + return cmd->finished; +#endif +} + +int finish_command(struct child_process *cmd) +{ + return wait_or_whine(cmd, /*block=*/true); +} + +int run_command(struct child_process *cmd) +{ + int code = start_command(cmd); + if (code) + return code; + return finish_command(cmd); +} + +static void prepare_run_command_v_opt(struct child_process *cmd, + const char **argv, + int opt) +{ + memset(cmd, 0, sizeof(*cmd)); + cmd->argv = argv; + cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0; + cmd->exec_cmd = opt & RUN_EXEC_CMD ? 1 : 0; + cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0; +} + +int run_command_v_opt(const char **argv, int opt) +{ + struct child_process cmd; + prepare_run_command_v_opt(&cmd, argv, opt); + return run_command(&cmd); +} -- cgit v1.3.1