CVE-2024-50213

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

drm/tests: hdmi: Fix memory leaks in drm_display_mode_from_cea_vic()

modprobe drm_hdmi_state_helper_test and then rmmod it, the following memory leak occurs.

The mode allocated in drm_mode_duplicate() called by drm_display_mode_from_cea_vic() is not freed, which cause the memory leak:

unreferenced object 0xffffff80ccd18100 (size 128):
  comm kunit_try_catch, pid 1851, jiffies 4295059695
  hex dump (first 32 bytes):
    57 62 00 00 80 02 90 02 f0 02 20 03 00 00 e0 01  Wb........ .....
    ea 01 ec 01 0d 02 00 00 0a 00 00 00 00 00 00 00  ................
  backtrace (crc c2f1aa95):
    [<000000000f10b11b>] kmemleak_alloc+0x34/0x40
    [<000000001cd4cf73>] __kmalloc_cache_noprof+0x26c/0x2f4
    [<00000000f1f3cffa>] drm_mode_duplicate+0x44/0x19c
    [<000000008cbeef13>] drm_display_mode_from_cea_vic+0x88/0x98
    [<0000000019daaacf>] 0xffffffedc11ae69c
    [<000000000aad0f85>] kunit_try_run_case+0x13c/0x3ac
    [<00000000a9210bac>] kunit_generic_run_threadfn_adapter+0x80/0xec
    [<000000000a0b2e9e>] kthread+0x2e8/0x374
    [<00000000bd668858>] ret_from_fork+0x10/0x20
......

Free mode by using drm_kunit_display_mode_from_cea_vic() to fix it.

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/3bc3fae8a0f22e0e713729b50e2111f6a8c64724
• https://git.kernel.org/stable/c/add4163aca0d4a86e9fe4aa513865e4237db8aef