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From: Petr Mladek <pmladek@suse.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"Tobin C . Harding" <me@tobin.cc>, Joe Perches <joe@perches.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.cz>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
	Kees Cook <keescook@chromium.org>
Subject: [PATCH v5 08/11] vsprintf: Factor out %pO handler as kobject_string()
Date: Wed, 25 Apr 2018 13:12:48 +0200	[thread overview]
Message-ID: <20180425111251.13246-9-pmladek@suse.com> (raw)
In-Reply-To: <20180425111251.13246-1-pmladek@suse.com>

Move code from the long pointer() function. We are going to add a check for
the access to the address that will make it even more complicated.

Also it is better to warn about unknown specifier instead of falling
back to the %p behavior. It will help people to understand what is
going wrong. They expect some device node names and not a pointer
in this situation.

In fact, this avoids leaking the address when invalid %pO format
specifier is used. The old code fallen back to printing the
non-hashed value.

Fixes: commit 7b1924a1d930eb27f ("vsprintf: add printk specifier %px")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tobin Harding <me@tobin.cc>
Cc: Kees Cook <keescook@chromium.org>
---
 lib/vsprintf.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index e58436ef9f7f..3536796c483c 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1769,6 +1769,17 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 	return widen_string(buf, buf - buf_start, end, spec);
 }
 
+static char *kobject_string(char *buf, char *end, void *ptr,
+			    struct printf_spec spec, const char *fmt)
+{
+	switch (fmt[1]) {
+	case 'F':
+		return device_node_string(buf, end, ptr, spec, fmt + 1);
+	}
+
+	return valid_string(buf, end, "(%pO?)", spec);
+}
+
 /*
  * Show a '%p' thing.  A kernel extension is that the '%p' is followed
  * by an extra set of alphanumeric characters that are extended format
@@ -1962,10 +1973,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 	case 'G':
 		return flags_string(buf, end, ptr, spec, fmt);
 	case 'O':
-		switch (fmt[1]) {
-		case 'F':
-			return device_node_string(buf, end, ptr, spec, fmt + 1);
-		}
+		return kobject_string(buf, end, ptr, spec, fmt);
 	case 'x':
 		return pointer_string(buf, end, ptr, spec);
 	}
-- 
2.13.6

  parent reply	other threads:[~2018-04-25 11:15 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-25 11:12 [PATCH v5 00/11] vsprintf: Prevent silent crashes and consolidate error handling Petr Mladek
2018-04-25 11:12 ` [PATCH v5 01/11] vsprintf: Shuffle misc pointer to string functions Petr Mladek
2018-04-25 14:57   ` Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 02/11] vsprintf: Add missing const ptr qualifier to prt_to_id() Petr Mladek
2018-04-25 14:57   ` Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 03/11] vsprintf: Consistent %pK handling for kptr_restrict == 0 Petr Mladek
2018-04-25 14:58   ` Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 04/11] vsprintf: Do not check address of well-known strings Petr Mladek
2018-04-25 11:44   ` Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 05/11] vsprintf: Consolidate handling of unknown pointer specifiers Petr Mladek
2018-04-25 13:08   ` Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 06/11] vsprintf: Factor out %p[iI] handler as ip_addr_string() Petr Mladek
2018-04-25 13:11   ` Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 07/11] vsprintf: Factor out %pV handler as va_format() Petr Mladek
2018-04-25 14:56   ` Andy Shevchenko
2018-04-25 11:12 ` Petr Mladek [this message]
2018-04-25 15:01   ` [PATCH v5 08/11] vsprintf: Factor out %pO handler as kobject_string() Andy Shevchenko
2018-04-25 11:12 ` [PATCH v5 09/11] vsprintf: Prevent crash when dereferencing invalid pointers Petr Mladek
2018-04-25 15:10   ` Andy Shevchenko
2018-04-25 15:32     ` Andy Shevchenko
2018-04-27 12:47     ` Petr Mladek
2018-05-03 11:55       ` Andy Shevchenko
2018-04-26 21:46   ` kbuild test robot
2018-04-25 11:12 ` [PATCH v5 10/11] vsprintf: WARN() on invalid pointer access Petr Mladek
2018-04-25 12:43   ` Rasmus Villemoes
2018-04-26  1:28   ` Sergey Senozhatsky
2018-04-27 12:37     ` Petr Mladek
2018-04-25 11:12 ` [PATCH v5 11/11] vsprintf: Avoid confusion between invalid address and value Petr Mladek
2018-04-27 14:10 ` [PATCH v5 00/11] vsprintf: Prevent silent crashes and consolidate error handling Petr Mladek

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