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-rw-r--r--kernel/trace/trace_probe_kernel.h31
1 files 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;
}
/* Return the length of string -- including null terminal byte */
@@ -34,7 +44,18 @@ kern_fetch_store_strlen(unsigned long addr)
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
- return (ret < 0) ? ret : len;
+ /* For faults, return enough to hold the FAULT_STRING */
+ return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
+}
+
+static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
+{
+ if (ret >= 0) {
+ *(u32 *)dest = make_data_loc(ret, __dest - base);
+ } else {
+ strscpy(__dest, FAULT_STRING, len);
+ ret = strlen(__dest) + 1;
+ }
}
/*
@@ -55,8 +76,7 @@ kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
__dest = get_loc_data(dest, base);
ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
- if (ret >= 0)
- *(u32 *)dest = make_data_loc(ret, __dest - base);
+ set_data_loc(ret, dest, __dest, base, maxlen);
return ret;
}
@@ -87,8 +107,7 @@ kern_fetch_store_string(unsigned long addr, void *dest, void *base)
* probing.
*/
ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
- if (ret >= 0)
- *(u32 *)dest = make_data_loc(ret, __dest - base);
+ set_data_loc(ret, dest, __dest, base, maxlen);
return ret;
}