CVE-2023-53857
Description
In the Linux kernel, the following vulnerability has been resolved:
bpf: bpf_sk_storage: Fix invalid wait context lockdep report
'./test_progs -t test_local_storage' reported a splat:
[ 27.137569] ============================= [ 27.138122] [ BUG: Invalid wait context ] [ 27.138650] 6.5.0-03980-gd11ae1b16b0a #247 Tainted: G O [ 27.139542] ----------------------------- [ 27.140106] test_progs/1729 is trying to lock: [ 27.140713] ffff8883ef047b88 (stock_lock){-.-.}-{3:3}, at: local_lock_acquire+0x9/0x130 [ 27.141834] other info that might help us debug this: [ 27.142437] context-{5:5} [ 27.142856] 2 locks held by test_progs/1729: [ 27.143352] #0: ffffffff84bcd9c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x4/0x40 [ 27.144492] #1: ffff888107deb2c0 (&storage->lock){..-.}-{2:2}, at: bpf_local_storage_update+0x39e/0x8e0 [ 27.145855] stack backtrace: [ 27.146274] CPU: 0 PID: 1729 Comm: test_progs Tainted: G O 6.5.0-03980-gd11ae1b16b0a #247 [ 27.147550] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 27.149127] Call Trace: [ 27.149490] [ 27.149867] dump_stack_lvl+0x130/0x1d0 [ 27.152609] dump_stack+0x14/0x20 [ 27.153131] __lock_acquire+0x1657/0x2220 [ 27.153677] lock_acquire+0x1b8/0x510 [ 27.157908] local_lock_acquire+0x29/0x130 [ 27.159048] obj_cgroup_charge+0xf4/0x3c0 [ 27.160794] slab_pre_alloc_hook+0x28e/0x2b0 [ 27.161931] __kmem_cache_alloc_node+0x51/0x210 [ 27.163557] __kmalloc+0xaa/0x210 [ 27.164593] bpf_map_kzalloc+0xbc/0x170 [ 27.165147] bpf_selem_alloc+0x130/0x510 [ 27.166295] bpf_local_storage_update+0x5aa/0x8e0 [ 27.167042] bpf_fd_sk_storage_update_elem+0xdb/0x1a0 [ 27.169199] bpf_map_update_value+0x415/0x4f0 [ 27.169871] map_update_elem+0x413/0x550 [ 27.170330] __sys_bpf+0x5e9/0x640 [ 27.174065] __x64_sys_bpf+0x80/0x90 [ 27.174568] do_syscall_64+0x48/0xa0 [ 27.175201] entry_SYSCALL_64_after_hwframe+0x6e/0xd8 [ 27.175932] RIP: 0033:0x7effb40e41ad [ 27.176357] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d8 [ 27.179028] RSP: 002b:00007ffe64c21fc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000141 [ 27.180088] RAX: ffffffffffffffda RBX: 00007ffe64c22768 RCX: 00007effb40e41ad [ 27.181082] RDX: 0000000000000020 RSI: 00007ffe64c22008 RDI: 0000000000000002 [ 27.182030] RBP: 00007ffe64c21ff0 R08: 0000000000000000 R09: 00007ffe64c22788 [ 27.183038] R10: 0000000000000064 R11: 0000000000000202 R12: 0000000000000000 [ 27.184006] R13: 00007ffe64c22788 R14: 00007effb42a1000 R15: 0000000000000000 [ 27.184958]
It complains about acquiring a local_lock while holding a raw_spin_lock. It means it should not allocate memory while holding a raw_spin_lock since it is not safe for RT.
raw_spin_lock is needed because bpf_local_storage supports tracing context. In particular for task local storage, it is easy to get a "current" task PTR_TO_BTF_ID in tracing bpf prog. However, task (and cgroup) local storage has already been moved to bpf mem allocator which can be used after raw_spin_lock.
The splat is for the sk storage. For sk (and inode) storage, it has not been moved to bpf mem allocator. Using raw_spin_lock or not, kzalloc(GFP_ATOMIC) could theoretically be unsafe in tracing context. However, the local storage helper requires a verifier accepted sk pointer (PTR_TO_BTF_ID), it is hypothetical if that (mean running a bpf prog in a kzalloc unsafe context and also able to hold a verifier accepted sk pointer) could happen.
This patch avoids kzalloc after raw_spin_lock to silent the splat. There is an existing kzalloc before the raw_spin_lock. At that point, a kzalloc is very likely required because a lookup has just been done before. Thus, this patch always does the kzalloc before acq ---truncated---
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A lockdep splat in the Linux kernel's BPF local storage code reveals an invalid wait context when memory allocation is performed while holding a spinlock under RCU read lock.
Root
Cause
The vulnerability is a lockdep-detected invalid wait context in the Linux kernel's BPF local storage subsystem. When bpf_local_storage_update is called, it holds a spinlock (storage->lock) while inside an RCU read-side critical section. The code path then attempts to allocate memory via bpf_selem_alloc, which calls kmalloc. This allocation can trigger obj_cgroup_charge, which acquires a local_lock (stock_lock). Because local_lock is a sleeping lock on RT kernels (or a lock that might sleep), acquiring it while holding a spinlock and under RCU read lock violates lock ordering rules, causing a BUG: Invalid wait context splat [1].
Attack
Surface
This issue is triggered by a user-space program using the bpf system call to update a BPF map of type BPF_MAP_TYPE_SK_STORAGE. The specific test case is test_progs -t test_local_storage. No special privileges beyond `CAP_BPF access to BPF are required; the bug manifests during normal BPF map update operations. The kernel configuration must include BPF and the relevant storage map types [1].
Impact
The impact is a kernel splat (lockdep warning) that can cause system instability, denial of service, or a kernel panic depending on the kernel configuration (e.g., if panic_on_lockdep is set). An unprivileged user with BPF access could potentially trigger this to disrupt system operation. The bug does not directly allow arbitrary code execution or privilege escalation, but it can lead to a system crash [1].
Mitigation
The fix is included in the Linux kernel commit 300415ca373a07782fcbc2f8d9429bc2dc27a47, which adjusts the locking or allocation strategy to avoid the invalid wait context. Users should apply the latest stable kernel updates that include this commit. No workaround is available other than avoiding the use of BPF local storage maps on affected kernels [1].
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2Patches
2300415caa373a96a44aba556Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
2News mentions
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