CVE-2019-9857

In the Linux kernel through 5.0.2, the function inotify_update_existing_watch() in fs/notify/inotify/inotify_user.c neglects to call fsnotify_put_mark() with IN_MASK_CREATE after fsnotify_find_mark(), which will cause a memory leak (aka refcount leak). Finally, this will cause a denial of service.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• http://www.securityfocus.com/bid/107527
• https://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git/commit/?h=fsnotify\u0026id=62c9d2674b31d4c8a674bee86b7edc6da2803aea
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NXLZ2V2ES37A3J7DMK4MZYIWV2LEZFLM/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PPH3B7FJOMWD5JWUPZKB6T44KNT4PX2L/
• https://patchwork.kernel.org/patch/10836283/
• https://security.netapp.com/advisory/ntap-20190404-0002/