CVE-2022-50477

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

rtc: class: Fix potential memleak in devm_rtc_allocate_device()

devm_rtc_allocate_device() will alloc a rtc_device first, and then run dev_set_name(). If dev_set_name() failed, the rtc_device will memleak. Move devm_add_action_or_reset() in front of dev_set_name() to prevent memleak.

unreferenced object 0xffff888110a53000 (size 2048): comm python3, pid 470, jiffies 4296078308 (age 58.882s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 08 30 a5 10 81 88 ff ff ………0…… 08 30 a5 10 81 88 ff ff 00 00 00 00 00 00 00 00 .0………….. backtrace: [<000000004aac0364>] kmalloc_trace+0x21/0x110 [<000000000ff02202>] devm_rtc_allocate_device+0xd4/0x400 [<000000001bdf5639>] devm_rtc_device_register+0x1a/0x80 [<00000000351bf81c>] rx4581_probe+0xdd/0x110 [rtc_rx4581] [<00000000f0eba0ae>] spi_probe+0xde/0x130 [<00000000bff89ee8>] really_probe+0x175/0x3f0 [<00000000128e8d84>] __driver_probe_device+0xe6/0x170 [<00000000ee5bf913>] device_driver_attach+0x32/0x80 [<00000000f3f28f92>] bind_store+0x10b/0x1a0 [<000000009ff812d8>] drv_attr_store+0x49/0x70 [<000000008139c323>] sysfs_kf_write+0x8d/0xb0 [<00000000b6146e01>] kernfs_fop_write_iter+0x214/0x2d0 [<00000000ecbe3895>] vfs_write+0x61a/0x7d0 [<00000000aa2196ea>] ksys_write+0xc8/0x190 [<0000000046a600f5>] do_syscall_64+0x37/0x90 [<00000000541a336f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

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

• https://git.kernel.org/stable/c/0bcfc8fd3e596994f527b46730579428b3a4fa5f
• https://git.kernel.org/stable/c/59457a0f079eae19aaf322b3cc1c8ba66f55c5f3
• https://git.kernel.org/stable/c/60da73808298ff2cfa9f165d55eb3d7aa7078601