From: Andrii Nakryiko andriin@fb.com
commit 02553b91da5deb63c8562b47529b09b734659af0 upstream.
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: 8d92db5c04d1 ("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 --- kernel/trace/bpf_trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a46256f99229..c4c825dcdef8 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -198,7 +198,7 @@ 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;