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.
