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Woojin Ji 9786008514 bpftool: Use libbpf error code for flow dissector query ... [ Upstream commit 8a7f2bff21 ] bpf_prog_query() returns a negative errno on failure. query_flow_dissector() currently closes the namespace fd and then reads errno to decide whether -EINVAL means that the running kernel does not support flow dissector queries. That errno check controls behavior, not just diagnostics: -EINVAL is handled as a non-fatal old-kernel case, while any other error makes bpftool net fail. The namespace fd is opened read-only, so close() is not expected to commonly fail in normal use. Still, the BPF_PROG_QUERY error is already available in err, and reading errno after an intervening close() is fragile. If close() does change errno, the compatibility branch may be based on close()'s error instead of the BPF_PROG_QUERY result. This was reproduced with an LD_PRELOAD fault injector that forced BPF_PROG_QUERY for BPF_FLOW_DISSECTOR to fail with EINVAL and then forced close() on the netns fd to fail with EIO. The unpatched bpftool reported "can't query prog: Input/output error". With this change, the same injected failure is handled as the intended non-fatal EINVAL compatibility case. Use the libbpf-returned error code instead. Keep the existing errno reset in the non-fatal path to preserve batch mode behavior. The success path is unchanged. Fixes: 7f0c57fec8 ("bpftool: show flow_dissector attachment status") Signed-off-by: Woojin Ji <random6.xyz@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20260603003339.33791-1-random6.xyz@gmail.com Assisted-by: ChatGPT:gpt-5.5 Signed-off-by: Sasha Levin <sashal@kernel.org>		History 2026-07-24 15:51:32 +02:00
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bpftool	bpftool: Use libbpf error code for flow dissector query	2026-07-24 15:51:32 +02:00
resolve_btfids	bpf: Fix potential integer overflow in resolve_btfids	2024-06-16 13:39:50 +02:00
runqslower	tools/runqslower: Use __state instead of state	2021-07-07 09:42:26 -07:00
.gitignore	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
bpf_asm.c	docs: networking: convert filter.txt to ReST	2020-04-28 14:39:46 -07:00
bpf_dbg.c	bpf: Simplify the calculation of variables	2021-03-04 19:24:53 -08:00
bpf_exp.l	bpf: fix cbpf parser bug for octal numbers	2018-06-03 07:46:55 -07:00
bpf_exp.y	tools, bpf_asm: Exit non-zero on errors	2021-02-26 22:53:50 +01:00
bpf_jit_disasm.c	tools bpf_jit_disasm: Fix compilation error with new binutils	2023-03-17 08:49:04 +01:00
Makefile	tools bpf_jit_disasm: Fix compilation error with new binutils	2023-03-17 08:49:04 +01:00