lib/vsprintf: Hash legacy clock addresses

geertu · pmladek · commit ec12bc2909f9 · 2018-10-12T11:24:41.000+02:00
On platforms using the Common Clock Framework, "%pC" prints the clock's name. On legacy platforms, it prints the unhashed clock's address, potentially leaking sensitive information regarding the kernel layout in memory. Avoid this leak by printing the hashed address instead. To distinguish between clocks, a 32-bit unique identifier is as good as an actual pointer value. Fixes: ad67b74 ("printk: hash addresses printed with %p") Link: http://lkml.kernel.org/r/20181011084249.4520-3-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>
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
@@ -420,9 +420,8 @@ struct clk
 	%pC	pll1
 	%pCn	pll1
 
-For printing struct clk structures. %pC and %pCn print the name
-(Common Clock Framework) or address (legacy clock framework) of the
-structure.
+For printing struct clk structures. %pC and %pCn print the name of the clock
+(Common Clock Framework) or a unique 32-bit ID (legacy clock framework).
 
 Passed by reference.
 
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
@@ -1563,7 +1563,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
 #ifdef CONFIG_COMMON_CLK
 		return string(buf, end, __clk_get_name(clk), spec);
 #else
-		return special_hex_number(buf, end, (unsigned long)clk, sizeof(unsigned long));
+		return ptr_to_id(buf, end, clk, spec);
 #endif
 	}
 }

Original file line number	Diff line number	Diff line change
`@@ -1563,7 +1563,7 @@ char clock(char buf, char end, struct clk clk, struct printf_spec spec,`
`1563`	`1563`	`#ifdef CONFIG_COMMON_CLK`
`1564`	`1564`	`return string(buf, end, __clk_get_name(clk), spec);`
`1565`	`1565`	`#else`
`1566`		`- return special_hex_number(buf, end, (unsigned long)clk, sizeof(unsigned long));`
	`1566`	`+ return ptr_to_id(buf, end, clk, spec);`
`1567`	`1567`	`#endif`
`1568`	`1568`	`}`
`1569`	`1569`	`}`