CVE-2024-38555

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

net/mlx5: Discard command completions in internal error

Fix use after free when FW completion arrives while device is in internal error state. Avoid calling completion handler in this case, since the device will flush the command interface and trigger all completions manually.

Kernel log: ————[ cut here ]———— refcount_t: underflow; use-after-free. … RIP: 0010:refcount_warn_saturate+0xd8/0xe0 … Call Trace: ? __warn+0x79/0x120 ? refcount_warn_saturate+0xd8/0xe0 ? report_bug+0x17c/0x190 ? handle_bug+0x3c/0x60 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? refcount_warn_saturate+0xd8/0xe0 cmd_ent_put+0x13b/0x160 [mlx5_core] mlx5_cmd_comp_handler+0x5f9/0x670 [mlx5_core] cmd_comp_notifier+0x1f/0x30 [mlx5_core] notifier_call_chain+0x35/0xb0 atomic_notifier_call_chain+0x16/0x20 mlx5_eq_async_int+0xf6/0x290 [mlx5_core] notifier_call_chain+0x35/0xb0 atomic_notifier_call_chain+0x16/0x20 irq_int_handler+0x19/0x30 [mlx5_core] __handle_irq_event_percpu+0x4b/0x160 handle_irq_event+0x2e/0x80 handle_edge_irq+0x98/0x230 __common_interrupt+0x3b/0xa0 common_interrupt+0x7b/0xa0 asm_common_interrupt+0x22/0x40

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/1337ec94bc5a9eed250e33f5f5c89a28a6bfabdb
• https://git.kernel.org/stable/c/1d5dce5e92a70274de67a59e1e674c3267f94cd7
• https://git.kernel.org/stable/c/3cb92b0ad73d3f1734e812054e698d655e9581b0
• https://git.kernel.org/stable/c/7ac4c69c34240c6de820492c0a28a0bd1494265a
• https://git.kernel.org/stable/c/bf8aaf0ae01c27ae3c06aa8610caf91e50393396
• https://git.kernel.org/stable/c/db9b31aa9bc56ff0d15b78f7e827d61c4a096e40
• https://git.kernel.org/stable/c/f6fbb8535e990f844371086ab2c1221f71f993d3