CVE-2024-50030

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

drm/xe/ct: prevent UAF in send_recv()

Ensure we serialize with completion side to prevent UAF with fence going out of scope on the stack, since we have no clue if it will fire after the timeout before we can erase from the xa. Also we have some dependent loads and stores for which we need the correct ordering, and we lack the needed barriers. Fix this by grabbing the ct->lock after the wait, which is also held by the completion side.

v2 (Badal):

• Also print done after acquiring the lock and seeing timeout.

(cherry picked from commit 52789ce35c55ccd30c4b67b9cc5b2af55e0122ea)

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References

• https://git.kernel.org/stable/c/8ed7dd4c55e4fb21531a9645aeb66a30eaf43a46
• https://git.kernel.org/stable/c/db7f92af626178ba59dbbcdd5dee9ec24a987a88