On 1/19/21 1:45 PM, Kees Cook wrote:
How about this so the base address is hashed once, with the offset added
to it for each line instead of each line having a "new" hash that makes
no sense:
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 9301578f98e8..20264828752d 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -242,12 +242,17 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
const void *buf, size_t len, bool ascii)
{
const u8 *ptr = buf;
+ const u8 *addr;
int i, linelen, remaining = len;
unsigned char linebuf[32 * 3 + 2 + 32 + 1];
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
+ if (prefix_type == DUMP_PREFIX_ADDRESS &&
+ ptr_to_hashval(ptr, &addr))
+ addr = 0;
+
for (i = 0; i < len; i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
@@ -258,7 +263,7 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
switch (prefix_type) {
case DUMP_PREFIX_ADDRESS:
printk("%s%s%p: %s\n",
- level, prefix_str, ptr + i, linebuf);
+ level, prefix_str, addr + i, linebuf);
Well, this is better than nothing, but not by much. Again, as long as
%px exists for printk(), I just cannot understand any resistance to
allowing it in print_hex_dump().
Frankly, I think this patch and my patch should both be added. During
debugging, it's very difficult if not impossible to work with hashed
addresses. I use print_hex_dump() with an unhashed address all the
time, either by applying my patch to my own kernel or just replacing the
%p with %px.
