tracing: Make trace_seq_putmem_hex() more robust
Currently trace_seq_putmem_hex() can only take as a parameter a pointer
to something that is 8 bytes or less, otherwise it will overflow the
buffer. This is protected by a macro that encompasses the call to
trace_seq_putmem_hex() that has a BUILD_BUG_ON() for the variable before
it is passed in. This is not very robust and if trace_seq_putmem_hex() ever
gets used outside that macro it will cause issues.
Instead of only being able to produce a hex output of memory that is for
a single word, change it to be more robust and allow any size input.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 0fabca7..88c0f80 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -291,6 +291,7 @@
}
EXPORT_SYMBOL_GPL(trace_seq_putmem);
+#define MAX_MEMHEX_BYTES 8U
#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
/**
@@ -310,22 +311,33 @@
{
unsigned char hex[HEX_CHARS];
const unsigned char *data = mem;
+ unsigned int start_len;
int i, j;
+ int cnt = 0;
if (s->full)
return 0;
+ while (len) {
+ start_len = min(len, HEX_CHARS - 1);
#ifdef __BIG_ENDIAN
- for (i = 0, j = 0; i < len; i++) {
+ for (i = 0, j = 0; i < start_len; i++) {
#else
- for (i = len-1, j = 0; i >= 0; i--) {
+ for (i = start_len-1, j = 0; i >= 0; i--) {
#endif
- hex[j++] = hex_asc_hi(data[i]);
- hex[j++] = hex_asc_lo(data[i]);
- }
- hex[j++] = ' ';
+ hex[j++] = hex_asc_hi(data[i]);
+ hex[j++] = hex_asc_lo(data[i]);
+ }
+ if (WARN_ON_ONCE(j == 0 || j/2 > len))
+ break;
- return trace_seq_putmem(s, hex, j);
+ /* j increments twice per loop */
+ len -= j / 2;
+ hex[j++] = ' ';
+
+ cnt += trace_seq_putmem(s, hex, j);
+ }
+ return cnt;
}
EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);