From: Rabin Vincent <rabin.vincent@axis.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, bp@suse.de,
Rabin Vincent <rabinv@axis.com>
Subject: [PATCH] printk: fix printk.devkmsg sysctl
Date: Fri, 27 Jan 2017 14:11:46 +0100 [thread overview]
Message-ID: <1485522706-18852-1-git-send-email-rabin.vincent@axis.com> (raw)
From: Rabin Vincent <rabinv@axis.com>
The comment says that it doesn't want to accept trailing crap but that's
just what it allows:
# echo -n offX > /proc/sys/kernel/printk_devkmsg
#
while at the same time it rejects legitimate uses:
# echo -n off > /proc/sys/kernel/printk_devkmsg
-sh: echo: write error: Invalid argument
Fix it.
Before this patch:
# cat /proc/sys/kernel/printk_devkmsg
ratelimit
# echo off > /proc/sys/kernel/printk_devkmsg
# sysctl -w kernel.printk_devkmsg=off
sysctl: short write
# echo -n off > /proc/sys/kernel/printk_devkmsg
-sh: echo: write error: Invalid argument
# echo -n offX > /proc/sys/kernel/printk_devkmsg
#
# printf "off\nX" >/proc/sys/kernel/printk_devkmsg
-sh: printf: write error: Invalid argument
After this patch:
# cat /proc/sys/kernel/printk_devkmsg
ratelimit
# echo off > /proc/sys/kernel/printk_devkmsg
# sysctl -w kernel.printk_devkmsg=off
kernel.printk_devkmsg = off
# echo -n off > /proc/sys/kernel/printk_devkmsg
# echo -n offX > /proc/sys/kernel/printk_devkmsg
-sh: echo: write error: Invalid argument
# printf "off\nX" >/proc/sys/kernel/printk_devkmsg
#
As a side effect, the "off\nX" case is not rejected anymore, but that is how
the other sysctl files behave:
# cat /proc/sys/kernel/printk_ratelimit
0
# printf "5\nX" >/proc/sys/kernel/printk_ratelimit
# cat /proc/sys/kernel/printk_ratelimit
5
Fixes: 750afe7babd117d ("printk: add kernel parameter to control writes to /dev/kmsg")
Signed-off-by: Rabin Vincent <rabinv@axis.com>
---
kernel/printk/printk.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8b26964..032b9e0 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -107,15 +107,15 @@ static int __control_devkmsg(char *str)
if (!str)
return -EINVAL;
- if (!strncmp(str, "on", 2)) {
+ if (!strcmp(str, "on")) {
devkmsg_log = DEVKMSG_LOG_MASK_ON;
- return 2;
- } else if (!strncmp(str, "off", 3)) {
+ return 0;
+ } else if (!strcmp(str, "off")) {
devkmsg_log = DEVKMSG_LOG_MASK_OFF;
- return 3;
- } else if (!strncmp(str, "ratelimit", 9)) {
+ return 0;
+ } else if (!strcmp(str, "ratelimit")) {
devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
- return 9;
+ return 0;
}
return -EINVAL;
}
@@ -177,7 +177,7 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
* Do not accept an unknown string OR a known string with
* trailing crap...
*/
- if (err < 0 || (err + 1 != *lenp)) {
+ if (err < 0) {
/* ... and restore old setting. */
devkmsg_log = old;
--
2.1.4
next reply other threads:[~2017-01-27 13:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-27 13:11 Rabin Vincent [this message]
2017-01-27 15:01 ` [PATCH] printk: fix printk.devkmsg sysctl Borislav Petkov
2017-01-27 15:42 ` Rabin Vincent
2017-01-27 18:19 ` Borislav Petkov
2017-01-30 13:38 ` Petr Mladek
2017-01-30 17:03 ` Borislav Petkov
2017-01-30 22:39 ` Borislav Petkov
2017-01-31 13:55 ` Petr Mladek
2017-02-02 4:50 ` Sergey Senozhatsky
2017-01-30 17:31 ` Rabin Vincent
2017-01-30 17:40 ` Borislav Petkov
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