linux-kernel - [PATCH 4.16 124/196] vsprintf: Do not preprocess non-dereferenced pointers for bprintf (%px and %pK)

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Message-Id: <20180422135110.669892022@linuxfoundation.org>
Date:   Sun, 22 Apr 2018 15:52:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 4.16 124/196] vsprintf: Do not preprocess non-dereferenced pointers for bprintf (%px and %pK)

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Steven Rostedt (VMware) <rostedt@...dmis.org>

commit 1e6338cfb50e244c445ad7d891b35385bd0ee757 upstream.

Commit 841a915d20c7b2 ("printf: Do not have bprintf dereference pointers")
would preprocess various pointers that are dereferenced in the bprintf()
because the recording and printing are done at two different times. Some
pointers stayed dereferenced in the ring buffer because user space could
handle them (namely "%pS" and friends). Pointers that are not dereferenced
should not be processed immediately but instead just saved directly.

Cc: stable@...r.kernel.org
Fixes: 841a915d20c7b2 ("printf: Do not have bprintf dereference pointers")
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 lib/vsprintf.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2591,6 +2591,8 @@ int vbin_printf(u32 *bin_buf, size_t siz
 			case 's':
 			case 'F':
 			case 'f':
+			case 'x':
+			case 'K':
 				save_arg(void *);
 				break;
 			default:
@@ -2765,6 +2767,8 @@ int bstr_printf(char *buf, size_t size,
 			case 's':
 			case 'F':
 			case 'f':
+			case 'x':
+			case 'K':
 				process = true;
 				break;
 			default: