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| author | Andrea Righi <arighi@nvidia.com> | 2024-12-17 20:58:13 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-12-17 16:09:24 -0800 |
| commit | 23579010cf0a12476e96a5f1acdf78a9c5843657 (patch) | |
| tree | 301e0adb9b91129f0276a2a66e66d252da1e10b9 /kernel/bpf | |
| parent | 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8 (diff) | |
| download | linux-23579010cf0a12476e96a5f1acdf78a9c5843657.tar.gz linux-23579010cf0a12476e96a5f1acdf78a9c5843657.tar.bz2 linux-23579010cf0a12476e96a5f1acdf78a9c5843657.zip | |
bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP
On x86-64 calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP
disabled can trigger the following bug, as pcpu_hot is unavailable:
[ 8.471774] BUG: unable to handle page fault for address: 00000000936a290c
[ 8.471849] #PF: supervisor read access in kernel mode
[ 8.471881] #PF: error_code(0x0000) - not-present page
Fix by inlining a return 0 in the !CONFIG_SMP case.
Fixes: 1ae6921009e5 ("bpf: inline bpf_get_smp_processor_id() helper")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241217195813.622568-1-arighi@nvidia.com
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f7f892a52a37..77f56674aaa9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -21281,11 +21281,15 @@ patch_map_ops_generic: * changed in some incompatible and hard to support * way, it's fine to back out this inlining logic */ +#ifdef CONFIG_SMP insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number); insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0); insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0); cnt = 3; - +#else + insn_buf[0] = BPF_ALU32_REG(BPF_XOR, BPF_REG_0, BPF_REG_0); + cnt = 1; +#endif new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; |