Unverified Commit 7d4e3fc0 authored Nov 13, 2024 by openeuler-ci-bot Committed by Gitee Nov 13, 2024

!13131 [OLK-6.6][Backport] exec: don't WARN for racy path_noexec check

Merge Pull Request from: @lazy2528 
 
    exec/uselib系统调用和remount(MS_NOEXEC)并发会有一个WARNON打印：
    
```
       execveat                           remount
    do_open_execat(path/bin)
      do_filp_open
        path_openat
          do_open
            may_open
              path_noexec() // PASS
                                        remount(path->mnt, MS_NOEXEC)
    WARNON(path_noexec(&file->f_path)) // path_noexec() checks fail
```

    
    do_open_execat对打开的二进制文件做了isreg和对应path_mnt的noexec检查（may_open中），但是后续
do_open_execat中又对path_mnt的noexec做了检查，中间对mnt做noexec remount可能导致第二次检查失败，触发
WARNON。

    
    对于这个问题，之前是通过去掉WARNING警告对应的代码行来规避这个问题，目前upstream已有更好的解决办法，建议同步
upstream社区补丁来修复这个问题。

#I8LX53 
 
Link:https://gitee.com/openeuler/kernel/pulls/13131

 

Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Zhang Peng <zhangpeng362@huawei.com>

parents 2e693d58 86be13fd

fs/exec.c

+20 −3

Original line number	Diff line number	Diff line
		@@ -142,6 +142,14 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
		if (IS_ERR(file))
		goto out;

		/*
		* Check do_open_execat() for an explanation.
		*/
		error = -EACCES;
		if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) \|\|
		path_noexec(&file->f_path))
		goto exit;

		error = -ENOEXEC;

		read_lock(&binfmt_lock);
		@@ -158,7 +166,7 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
		break;
		}
		read_unlock(&binfmt_lock);

		exit:
		fput(file);
		out:
		return error;
		@@ -915,13 +923,22 @@ static struct file do_open_execat(int fd, struct filename name, int flags)

		file = do_filp_open(fd, name, &open_exec_flags);
		if (IS_ERR(file))
		goto out;
		return file;

		/*
		* In the past the regular type check was here. It moved to may_open() in
		* 633fb6ac3980 ("exec: move S_ISREG() check earlier"). Since then it is
		* an invariant that all non-regular files error out before we get here.
		*/
		err = -EACCES;
		if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) \|\|
		path_noexec(&file->f_path))
		goto exit;

		err = deny_write_access(file);
		if (err)
		goto exit;

		out:
		return file;

		exit: