All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Bruno Prémont" <bonbons@linux-vserver.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Jiri Kosina <jkosina@suse.cz>,
	linux-input@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] HID: picoLCD: off by one in dump_buff_as_hex()
Date: Wed, 19 Sep 2012 19:35:35 +0000	[thread overview]
Message-ID: <20120919213535.34712fb5@neptune.home> (raw)
In-Reply-To: <20120917225437.6f2847ee@neptune.home>

Dan,

What's your opinion on below alternative patch?
In addition to yours it makes would-overflow visible.

It does not check for output buffer having non-zero size but
as callers are local with #defined buffer size I don't think that would
be needed.





Author: Bruno Prémont <bonbons@linux-vserver.org>
Date:   Wed Sep 19 21:18:10 2012 +0200
Subject: HID: picoLCD: bounds check in dump_buff_as_hex()

Make sure we keep enough space for terminating NUL character after last
newline. If we have too much data, replace last byte with '.'s to
make overflow visible.

Using hex_dump_to_buffer() is not interesting as it adds more overhead
and does not append the trailing linefeed.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
---
 drivers/hid/hid-picolcd_debugfs.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-picolcd_debugfs.c b/drivers/hid/hid-picolcd_debugfs.c
index 868853a..c5c2fd9 100644
--- a/drivers/hid/hid-picolcd_debugfs.c
+++ b/drivers/hid/hid-picolcd_debugfs.c
@@ -381,16 +381,16 @@ static void dump_buff_as_hex(char *dst, size_t dst_sz, const u8 *data,
 		const size_t data_len)
 {
 	int i, j;
-	for (i = j = 0; i < data_len && j + 3 < dst_sz; i++) {
+	for (i = j = 0; i < data_len && j + 4 < dst_sz; i++) {
 		dst[j++] = hex_asc[(data[i] >> 4) & 0x0f];
 		dst[j++] = hex_asc[data[i] & 0x0f];
 		dst[j++] = ' ';
 	}
-	if (j < dst_sz) {
-		dst[j--] = '\0';
-		dst[j] = '\n';
-	} else
-		dst[j] = '\0';
+	dst[j]   = '\0';
+	if (j > 0)
+		dst[j-1] = '\n';
+	if (i < data_len && j > 2)
+		dst[j-2] = dst[j-3] = '.';
 }
 
 void picolcd_debug_out_report(struct picolcd_data *data,

WARNING: multiple messages have this Message-ID (diff)
From: "Bruno Prémont" <bonbons@linux-vserver.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Jiri Kosina <jkosina@suse.cz>,
	linux-input@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] HID: picoLCD: off by one in dump_buff_as_hex()
Date: Wed, 19 Sep 2012 21:35:35 +0200	[thread overview]
Message-ID: <20120919213535.34712fb5@neptune.home> (raw)
In-Reply-To: <20120917225437.6f2847ee@neptune.home>

Dan,

What's your opinion on below alternative patch?
In addition to yours it makes would-overflow visible.

It does not check for output buffer having non-zero size but
as callers are local with #defined buffer size I don't think that would
be needed.





Author: Bruno Prémont <bonbons@linux-vserver.org>
Date:   Wed Sep 19 21:18:10 2012 +0200
Subject: HID: picoLCD: bounds check in dump_buff_as_hex()

Make sure we keep enough space for terminating NUL character after last
newline. If we have too much data, replace last byte with '.'s to
make overflow visible.

Using hex_dump_to_buffer() is not interesting as it adds more overhead
and does not append the trailing linefeed.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
---
 drivers/hid/hid-picolcd_debugfs.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-picolcd_debugfs.c b/drivers/hid/hid-picolcd_debugfs.c
index 868853a..c5c2fd9 100644
--- a/drivers/hid/hid-picolcd_debugfs.c
+++ b/drivers/hid/hid-picolcd_debugfs.c
@@ -381,16 +381,16 @@ static void dump_buff_as_hex(char *dst, size_t dst_sz, const u8 *data,
 		const size_t data_len)
 {
 	int i, j;
-	for (i = j = 0; i < data_len && j + 3 < dst_sz; i++) {
+	for (i = j = 0; i < data_len && j + 4 < dst_sz; i++) {
 		dst[j++] = hex_asc[(data[i] >> 4) & 0x0f];
 		dst[j++] = hex_asc[data[i] & 0x0f];
 		dst[j++] = ' ';
 	}
-	if (j < dst_sz) {
-		dst[j--] = '\0';
-		dst[j] = '\n';
-	} else
-		dst[j] = '\0';
+	dst[j]   = '\0';
+	if (j > 0)
+		dst[j-1] = '\n';
+	if (i < data_len && j > 2)
+		dst[j-2] = dst[j-3] = '.';
 }
 
 void picolcd_debug_out_report(struct picolcd_data *data,
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

  reply	other threads:[~2012-09-19 19:35 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-14 11:04 [patch] HID: picoLCD: off by one in dump_buff_as_hex() Dan Carpenter
2012-09-14 11:04 ` Dan Carpenter
2012-09-17 20:54 ` Bruno Prémont
2012-09-17 20:54   ` Bruno Prémont
2012-09-19 19:35   ` Bruno Prémont [this message]
2012-09-19 19:35     ` Bruno Prémont
2012-09-22 12:55     ` Dan Carpenter
2012-09-22 12:55       ` Dan Carpenter
2012-09-24 21:07       ` Jiri Kosina
2012-09-24 21:07         ` Jiri Kosina

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20120919213535.34712fb5@neptune.home \
    --to=bonbons@linux-vserver.org \
    --cc=dan.carpenter@oracle.com \
    --cc=jkosina@suse.cz \
    --cc=kernel-janitors@vger.kernel.org \
    --cc=linux-input@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.