From: Steven Rostedt
Sent: 12 October 2022 11:41
Have the specific functions for kernel probes that read strings to inject the "(fault)" name directly. trace_probes.c does this too (for uprobes) but as the code to read strings are going to be used by synthetic events (and perhaps other utilities), it simplifies the code by making sure those other uses do not need to implement the "(fault)" name injection as well.
Cc: stable@vger.kernel.org Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org
kernel/trace/trace_probe_kernel.h | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h index 1d43df29a1f8..77dbd9ff9782 100644 --- a/kernel/trace/trace_probe_kernel.h +++ b/kernel/trace/trace_probe_kernel.h @@ -2,6 +2,8 @@ #ifndef __TRACE_PROBE_KERNEL_H_ #define __TRACE_PROBE_KERNEL_H_
+#define FAULT_STRING "(fault)"
/*
- This depends on trace_probe.h, but can not include it due to
- the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
@@ -13,8 +15,16 @@ static nokprobe_inline int kern_fetch_store_strlen_user(unsigned long addr) { const void __user *uaddr = (__force const void __user *)addr;
- int ret;
- return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
- ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
- /*
* strnlen_user_nofault returns zero on fault, insert the* FAULT_STRING when that occurs.*/- if (ret <= 0)
return strlen(FAULT_STRING) + 1;- return ret;
}
Isn't that going to do the wrong thing if the user string is valid memory but just zero length??
David
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