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lib/vsprintf: Hash printed address for netdev bits fallback

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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: ad67b74d24 ("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>
This commit is contained in:
Geert Uytterhoeven 2018-10-11 10:42:49 +02:00 committed by Petr Mladek
parent ec12bc2909
commit 431bca2430
1 changed files with 4 additions and 5 deletions
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9
lib/vsprintf.c
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@ -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':