Commit 02553b91 authored Jun 15, 2020 by Andrii Nakryiko Committed by Daniel Borkmann Jun 17, 2020

bpf: bpf_probe_read_kernel_str() has to return amount of data read on success

During recent refactorings, bpf_probe_read_kernel_str() started returning 0 on
success, instead of amount of data successfully read. This majorly breaks
applications relying on bpf_probe_read_kernel_str() and bpf_probe_read_str()
and their results. Fix this by returning actual number of bytes read.

Fixes: 8d92db5c ("bpf: rework the compat kernel probe handling")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616050432.1902042-1-andriin@fb.com

parent 6903cdae

kernel/trace/bpf_trace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -241,7 +241,7 @@ bpf_probe_read_kernel_str_common(void dst, u32 size, const void unsafe_ptr)
		if (unlikely(ret < 0))
		goto fail;

		return 0;
		return ret;
		fail:
		memset(dst, 0, size);
		return ret;