CVE-2024-26831

In the Linux kernel, the following vulnerability has been resolved:

net/handshake: Fix handshake_req_destroy_test1

Recently, handshake_req_destroy_test1 started failing:

Expected handshake_req_destroy_test == req, but handshake_req_destroy_test == 0000000000000000 req == 0000000060f99b40 not ok 11 req_destroy works

This is because sock_release(sock) was replaced with fput(filp) to address a memory leak. Note that sock_release() is synchronous but fput() usually delays the final close and clean-up.

The delay is not consequential in the other cases that were changed but handshake_req_destroy_test1 is testing that handshake_req_cancel() followed by closing the file actually does call the ->hp_destroy method. Thus the PTR_EQ test at the end has to be sure that the final close is complete before it checks the pointer.

We cannot use a completion here because if ->hp_destroy is never called (ie, there is an API bug) then the test will hang.

Reported by: Guenter Roeck linux@roeck-us.net

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

• https://git.kernel.org/stable/c/4e1d71cabb19ec2586827adfc60d68689c68c194
• https://git.kernel.org/stable/c/7f97805b8df6e33850e225e6bd3ebd9e246920af
• https://git.kernel.org/stable/c/d74226e03df1bf19848f18344401f254345af912
• https://git.kernel.org/stable/c/4e1d71cabb19ec2586827adfc60d68689c68c194
• https://git.kernel.org/stable/c/7f97805b8df6e33850e225e6bd3ebd9e246920af
• https://git.kernel.org/stable/c/d74226e03df1bf19848f18344401f254345af912