CVE-2021-47300 — bpf: Fix tail_call_reachable rejection for interpreter when jit failed

Affected: Linux

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

bpf: Fix tail_call_reachable rejection for interpreter when jit failed

During testing of f263a81451c1 ("bpf: Track subprog poke descriptors correctly and fix use-after-free") under various failure conditions, for example, when jit_subprogs() fails and tries to clean up the program to be run under the interpreter, we ran into the following freeze:

[...] #127/8 tailcall_bpf2bpf_3:FAIL [...] [ 92.041251] BUG: KASAN: slab-out-of-bounds in ___bpf_prog_run+0x1b9d/0x2e20 [ 92.042408] Read of size 8 at addr ffff88800da67f68 by task test_progs/682 [ 92.043707] [ 92.044030] CPU: 1 PID: 682 Comm: test_progs Tainted: G O 5.13.0-53301-ge6c08cb33a30-dirty #87 [ 92.045542] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 [ 92.046785] Call Trace: [ 92.047171] ? __bpf_prog_run_args64+0xc0/0xc0 [ 92.047773] ? __bpf_prog_run_args32+0x8b/0xb0 [ 92.048389] ? __bpf_prog_run_args64+0xc0/0xc0 [ 92.049019] ? ktime_get+0x117/0x130 [...] // few hundred [similar] lines more [ 92.659025] ? ktime_get+0x117/0x130 [ 92.659845] ? __bpf_prog_run_args64+0xc0/0xc0 [ 92.660738] ? __bpf_prog_run_args32+0x8b/0xb0 [ 92.661528] ? __bpf_prog_run_args64+0xc0/0xc0 [ 92.662378] ? print_usage_bug+0x50/0x50 [ 92.663221] ? print_usage_bug+0x50/0x50 [ 92.664077] ? bpf_ksym_find+0x9c/0xe0 [ 92.664887] ? ktime_get+0x117/0x1…

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CVE-2021-47300 — bpf: Fix tail_call_reachable rejection for interpreter when jit failed