CVE-2025-40287

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> exfat: fix improper check of dentry.stream.valid_size<br /> <br /> We found an infinite loop bug in the exFAT file system that can lead to a<br /> Denial-of-Service (DoS) condition. When a dentry in an exFAT filesystem is<br /> malformed, the following system calls — SYS_openat, SYS_ftruncate, and<br /> SYS_pwrite64 — can cause the kernel to hang.<br /> <br /> Root cause analysis shows that the size validation code in exfat_find()<br /> does not check whether dentry.stream.valid_size is negative. As a result,<br /> the system calls mentioned above can succeed and eventually trigger the DoS<br /> issue.<br /> <br /> This patch adds a check for negative dentry.stream.valid_size to prevent<br /> this vulnerability.