linux-kernel - [PATCH AUTOSEL 4.19 030/237] gsmi: Fix bug in append_to

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20191116154113.7417-30-sashal@kernel.org>
Date:   Sat, 16 Nov 2019 10:37:45 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Duncan Laurie <dlaurie@...omium.org>,
        Vadim Bendebury <vbendeb@...omium.org>,
        Stefan Reinauer <reinauer@...omium.org>,
        Furquan Shaikh <furquan@...gle.com>,
        Furquan Shaikh <furquan@...omium.org>,
        Aaron Durbin <adurbin@...omium.org>,
        Justin TerAvest <teravest@...omium.org>,
        Ross Zwisler <zwisler@...gle.com>,
        Guenter Roeck <groeck@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 030/237] gsmi: Fix bug in append_to_eventlog sysfs handler

From: Duncan Laurie <dlaurie@...omium.org>

[ Upstream commit 655603de68469adaff16842ac17a5aec9c9ce89b ]

The sysfs handler should return the number of bytes consumed, which in the
case of a successful write is the entire buffer.  Also fix a bug where
param.data_len was being set to (count - (2 * sizeof(u32))) instead of just
(count - sizeof(u32)).  The latter is correct because we skip over the
leading u32 which is our param.type, but we were also incorrectly
subtracting sizeof(u32) on the line where we were actually setting
param.data_len:

	param.data_len = count - sizeof(u32);

This meant that for our example event.kernel_software_watchdog with total
length 10 bytes, param.data_len was just 2 prior to this change.

To test, successfully append an event to the log with gsmi sysfs.
This sample event is for a "Kernel Software Watchdog"

> xxd -g 1 event.kernel_software_watchdog
0000000: 01 00 00 00 ad de 06 00 00 00

> cat event.kernel_software_watchdog > /sys/firmware/gsmi/append_to_eventlog

> mosys eventlog list | tail -1
14 | 2012-06-25 10:14:14 | Kernl Event | Software Watchdog

Signed-off-by: Duncan Laurie <dlaurie@...omium.org>
Reviewed-by: Vadim Bendebury <vbendeb@...omium.org>
Reviewed-by: Stefan Reinauer <reinauer@...omium.org>
Signed-off-by: Furquan Shaikh <furquan@...gle.com>
Tested-by: Furquan Shaikh <furquan@...omium.org>
Reviewed-by: Aaron Durbin <adurbin@...omium.org>
Reviewed-by: Justin TerAvest <teravest@...omium.org>
[zwisler: updated changelog for 2nd bug fix and upstream]
Signed-off-by: Ross Zwisler <zwisler@...gle.com>
Reviewed-by: Guenter Roeck <groeck@...omium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/firmware/google/gsmi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c
index c8f169bf2e27d..62337be07afcb 100644
--- a/drivers/firmware/google/gsmi.c
+++ b/drivers/firmware/google/gsmi.c
@@ -480,11 +480,10 @@ static ssize_t eventlog_write(struct file *filp, struct kobject *kobj,
 	if (count < sizeof(u32))
 		return -EINVAL;
 	param.type = *(u32 *)buf;
-	count -= sizeof(u32);
 	buf += sizeof(u32);
 
 	/* The remaining buffer is the data payload */
-	if (count > gsmi_dev.data_buf->length)
+	if ((count - sizeof(u32)) > gsmi_dev.data_buf->length)
 		return -EINVAL;
 	param.data_len = count - sizeof(u32);
 
@@ -504,7 +503,7 @@ static ssize_t eventlog_write(struct file *filp, struct kobject *kobj,
 
 	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
 
-	return rc;
+	return (rc == 0) ? count : rc;
 
 }
 
-- 
2.20.1