From 91efafb1dd8f471177a3dddb4841d75d3df1cc46 Mon Sep 17 00:00:00 2001 From: Shunyong Yang Date: Fri, 16 Feb 2018 23:07:09 +0200 Subject: lib/vsprintf: Replace space with '_' before crng is ready Before crng is ready, output of "%p" composes of "(ptrval)" and left padding spaces for alignment as no random address can be generated. This seems a little strange when default string width is larger than strlen("(ptrval)"). For example, when irq domain names are built with "%p", the nodes under /sys/kernel/debug/irq/domains like this on AArch64 system, [root@y irq]# ls domains/ default irqchip@ (ptrval)-2 irqchip@ (ptrval)-4 \_SB_.TCS0.QIC1 \_SB_.TCS0.QIC3 irqchip@ (ptrval) irqchip@ (ptrval)-3 \_SB_.TCS0.QIC0 \_SB_.TCS0.QIC2 The name "irqchip@ (ptrval)-2" is not so readable in console output. This patch replaces space with readable "_" when output needs padding. Following is the output after applying the patch, [root@y domains]# ls default irqchip@(____ptrval____)-2 irqchip@(____ptrval____)-4 \_SB_.TCS0.QIC1 \_SB_.TCS0.QIC3 irqchip@(____ptrval____) irqchip@(____ptrval____)-3 \_SB_.TCS0.QIC0 \_SB_.TCS0.QIC2 There is same problem in some subsystem's dmesg output. Moreover, someone may call "%p" in a similar case. In addition, the timing of crng initialization done may vary on different system. So, the change is made in vsprintf.c. Suggested-by: Rasmus Villemoes Link: http://lkml.kernel.org/r/20180216210711.79901-7-andriy.shevchenko@linux.intel.com To: "Tobin C . Harding" To: linux@rasmusvillemoes.dk To: Joe Perches To: linux-kernel@vger.kernel.org To: Andrew Morton Cc: Joey Zheng Signed-off-by: Shunyong Yang Signed-off-by: Andy Shevchenko Signed-off-by: Petr Mladek --- lib/vsprintf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'lib/vsprintf.c') diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 9004bbb..97be2d0 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1681,12 +1681,13 @@ early_initcall(initialize_ptr_random); /* Maps a pointer to a 32 bit unique identifier. */ static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec) { + const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)"; unsigned long hashval; if (unlikely(!have_filled_random_ptr_key)) { spec.field_width = 2 * sizeof(ptr); /* string length must be less than default_width */ - return string(buf, end, "(ptrval)", spec); + return string(buf, end, str, spec); } #ifdef CONFIG_64BIT -- cgit v1.1