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| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-09-04 10:43:19 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-09-04 07:58:36 -0700 |
| commit | 6668ed271eaefaa63e686bdfbedaeb7b8e492722 (patch) | |
| tree | 58e8288fead484f6755ad0815fc74c3742663761 /arch/arm64/lib/tishift.S | |
| download | linux-stable-6668ed271eaefaa63e686bdfbedaeb7b8e492722.tar.gz linux-stable-6668ed271eaefaa63e686bdfbedaeb7b8e492722.zip | |
selftests/bpf: Reject graph kptr use after RCU unlockgrafted
Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.
Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.
Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.
Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/arm64/lib/tishift.S')
| -rw-r--r-- | arch/arm64/lib/tishift.S | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/arch/arm64/lib/tishift.S b/arch/arm64/lib/tishift.S new file mode 100644 index 000000000..a88613834 --- /dev/null +++ b/arch/arm64/lib/tishift.S @@ -0,0 +1,74 @@ +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) + * + * Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. + */ + +#include <linux/linkage.h> + +#include <asm/assembler.h> + +SYM_FUNC_START(__ashlti3) + cbz x2, 1f + mov x3, #64 + sub x3, x3, x2 + cmp x3, #0 + b.le 2f + lsl x1, x1, x2 + lsr x3, x0, x3 + lsl x2, x0, x2 + orr x1, x1, x3 + mov x0, x2 +1: + ret +2: + neg w1, w3 + mov x2, #0 + lsl x1, x0, x1 + mov x0, x2 + ret +SYM_FUNC_END(__ashlti3) +EXPORT_SYMBOL(__ashlti3) + +SYM_FUNC_START(__ashrti3) + cbz x2, 1f + mov x3, #64 + sub x3, x3, x2 + cmp x3, #0 + b.le 2f + lsr x0, x0, x2 + lsl x3, x1, x3 + asr x2, x1, x2 + orr x0, x0, x3 + mov x1, x2 +1: + ret +2: + neg w0, w3 + asr x2, x1, #63 + asr x0, x1, x0 + mov x1, x2 + ret +SYM_FUNC_END(__ashrti3) +EXPORT_SYMBOL(__ashrti3) + +SYM_FUNC_START(__lshrti3) + cbz x2, 1f + mov x3, #64 + sub x3, x3, x2 + cmp x3, #0 + b.le 2f + lsr x0, x0, x2 + lsl x3, x1, x3 + lsr x2, x1, x2 + orr x0, x0, x3 + mov x1, x2 +1: + ret +2: + neg w0, w3 + mov x2, #0 + lsr x0, x1, x0 + mov x1, x2 + ret +SYM_FUNC_END(__lshrti3) +EXPORT_SYMBOL(__lshrti3) |