CVE-2022-49784

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

perf/x86/amd/uncore: Fix memory leak for events array

When a CPU comes online, the per-CPU NB and LLC uncore contexts are freed but not the events array within the context structure. This causes a memory leak as identified by the kmemleak detector.

[...] unreferenced object 0xffff8c5944b8e320 (size 32): comm "swapper/0", pid 1, jiffies 4294670387 (age 151.072s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<000000000759fb79>] amd_uncore_cpu_up_prepare+0xaf/0x230 [<00000000ddc9e126>] cpuhp_invoke_callback+0x2cf/0x470 [<0000000093e727d4>] cpuhp_issue_call+0x14d/0x170 [<0000000045464d54>] __cpuhp_setup_state_cpuslocked+0x11e/0x330 [<0000000069f67cbd>] __cpuhp_setup_state+0x6b/0x110 [<0000000015365e0f>] amd_uncore_init+0x260/0x321 [<00000000089152d2>] do_one_initcall+0x3f/0x1f0 [<000000002d0bd18d>] kernel_init_freeable+0x1ca/0x212 [<0000000030be8dde>] kernel_init+0x11/0x120 [<0000000059709e59>] ret_from_fork+0x22/0x30 unreferenced object 0xffff8c5944b8dd40 (size 64): comm "swapper/0", pid 1, jiffies 4294670387 (age 151.072s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000306efe8b>] amd_uncore_cpu_up_prepare+0x183/0x230 [<00000000ddc9e126>] cpuhp_invoke_callback+0x2cf/0x470 [<0000000093e727d4>] cpuhp_issue_call+0x14d/0x170 [<0000000045464d54>] __cpuhp_setup_state_cpuslocked+0x11e/0x330 [<0000000069f67cbd>] __cpuhp_setup_state+0x6b/0x110 [<0000000015365e0f>] amd_uncore_init+0x260/0x321 [<00000000089152d2>] do_one_initcall+0x3f/0x1f0 [<000000002d0bd18d>] kernel_init_freeable+0x1ca/0x212 [<0000000030be8dde>] kernel_init+0x11/0x120 [<0000000059709e59>] ret_from_fork+0x22/0x30 [...]

Fix the problem by freeing the events array before freeing the uncore context.

A memory leak was found in the AMD uncore performance monitoring driver (perf/x86/amd/uncore) due to the failure to free the events array when per-CPU uncore contexts are destroyed.

While this does not pose a direct security threat, it can lead to gradual memory exhaustion in systems with frequent CPU hotplug events or long-running perf workloads on AMD systems.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.