Commit 431bca24 authored Oct 11, 2018 by Geert Uytterhoeven Committed by Petr Mladek Oct 12, 2018

lib/vsprintf: Hash printed address for netdev bits fallback

The handler for "%pN" falls back to printing the raw pointer value when
using a different format than the (sole supported) special format
"%pNF", potentially leaking sensitive information regarding the kernel
layout in memory.

Avoid this leak by printing the hashed address instead.
Note that there are no in-tree users of the fallback.

Fixes: ad67b74d ("printk: hash addresses printed with %p")
Link: http://lkml.kernel.org/r/20181011084249.4520-4-geert+renesas@glider.be


To: "Tobin C . Harding" <me@tobin.cc>
To: Andrew Morton <akpm@linux-foundation.org>
To: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

parent ec12bc29

lib/vsprintf.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -1510,7 +1510,8 @@ char restricted_pointer(char buf, char end, const void ptr,
		}

		static noinline_for_stack
		char netdev_bits(char buf, char end, const void addr, const char *fmt)
		char netdev_bits(char buf, char end, const void addr,
		struct printf_spec spec, const char *fmt)
		{
		unsigned long long num;
		int size;
		@@ -1521,9 +1522,7 @@ char netdev_bits(char buf, char end, const void addr, const char *fmt)
		size = sizeof(netdev_features_t);
		break;
		default:
		num = (unsigned long)addr;
		size = sizeof(unsigned long);
		break;
		return ptr_to_id(buf, end, addr, spec);
		}

		return special_hex_number(buf, end, num, size);
		@@ -1945,7 +1944,7 @@ char pointer(const char fmt, char buf, char end, void *ptr,
		break;
		return restricted_pointer(buf, end, ptr, spec);
		case 'N':
		return netdev_bits(buf, end, ptr, fmt);
		return netdev_bits(buf, end, ptr, spec, fmt);
		case 'a':
		return address_val(buf, end, ptr, fmt);
		case 'd':

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