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, making the memory unavailable for reallocation and reuse.

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/
• 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/