Brendan Jackman b29dd96b90 bpf, x86: Fix BPF_FETCH atomic and/or/xor with r0 as src ... This code generates a CMPXCHG loop in order to implement atomic_fetch bitwise operations. Because CMPXCHG is hard-coded to use rax (which holds the BPF r0 value), it saves the _real_ r0 value into the internal "ax" temporary register and restores it once the loop is complete. In the middle of the loop, the actual bitwise operation is performed using src_reg. The bug occurs when src_reg is r0: as described above, r0 has been clobbered and the real r0 value is in the ax register. Therefore, perform this operation on the ax register instead, when src_reg is r0. Fixes: 981f94c3e9 ("bpf: Add bitwise atomic instructions") Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210216125307.1406237-1-jackmanb@google.com		2021-02-22 18:03:11 +01:00
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Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
bpf_jit_comp.c	bpf, x86: Fix BPF_FETCH atomic and/or/xor with r0 as src	2021-02-22 18:03:11 +01:00
bpf_jit_comp32.c	bpf: Rename BPF_XADD and prepare to encode other atomics in .imm	2021-01-14 18:34:29 -08:00