In the Linux kernel, the following vulnerability has been resolved: exfat: fix improper check of dentry.stream.validsize We found an infinite loop bug in the exFAT file system that can lead to a Denial-of-Service (DoS) condition. When a dentry in an exFAT filesystem is malformed, the following system calls — SYSopenat, SYSftruncate, and SYSpwrite64 — can cause the kernel to hang. Root cause analysis shows that the size validation code in exfatfind() does not check whether dentry.stream.validsize is negative. As a result, the system calls mentioned above can succeed and eventually trigger the DoS issue. This patch adds a check for negative dentry.stream.valid_size to prevent this vulnerability.