CWE-367 检查时间与使用时间(TOCTOU)的竞争条件 类漏洞列表 476

The following code checks a file, then updates its contents.

struct stat *sb; ... lstat("...",sb); // it has not been updated since the last time it was read printf("stated file\n"); if (sb->st_mtimespec==...){ print("Now updating things\n"); updateThings(); }

The following code is from a program installed setuid root. The program performs certain file operations on behalf of non-privileged users, and uses access checks to ensure that it does not use its root privileges to perform operations that should otherwise be unavailable the current user. The program uses the access() system call to check if the person running the program has permission to access…

if(!access(file,W_OK)) { f = fopen(file,"w+"); operate(f); ... } else { fprintf(stderr,"Unable to open file %s.\n",file); }