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Date: Tue, 12 Jan 2021 11:31:55 +0800 From: Xiaoming Ni <nixiaoming@...wei.com> To: <linux-kernel@...r.kernel.org>, <mcgrof@...nel.org>, <keescook@...omium.org>, <yzaikin@...gle.com>, <adobriyan@...il.com>, <linux-fsdevel@...r.kernel.org>, <vbabka@...e.cz>, <akpm@...ux-foundation.org>, <mhocko@...e.com>, <andy.shevchenko@...il.com> CC: <nixiaoming@...wei.com>, <wangle6@...wei.com> Subject: [PATCH v3] proc_sysctl: fix oops caused by incorrect command parameters. The process_sysctl_arg() does not check whether val is empty before invoking strlen(val). If the command line parameter () is incorrectly configured and val is empty, oops is triggered. For example: "hung_task_panic=1" is incorrectly written as "hung_task_panic", oops is triggered. The call stack is as follows: Kernel command line: .... hung_task_panic ...... Call trace: __pi_strlen+0x10/0x98 parse_args+0x278/0x344 do_sysctl_args+0x8c/0xfc kernel_init+0x5c/0xf4 ret_from_fork+0x10/0x30 To fix it, check whether "val" is empty when "phram" is a sysctl field. Error codes are returned in the failure branch, and error logs are generated by parse_args(). Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters from kernel command line") Signed-off-by: Xiaoming Ni <nixiaoming@...wei.com> --------- v3: Return -EINVAL, When phram is the sysctl field and val is empty. v2: https://lore.kernel.org/lkml/20210108023339.55917-1-nixiaoming@huawei.com/ Added log output of the failure branch based on the review comments of Kees Cook. v1: https://lore.kernel.org/lkml/20201224074256.117413-1-nixiaoming@huawei.com/ --------- --- fs/proc/proc_sysctl.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 317899222d7f..d493a50058a5 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -1770,6 +1770,9 @@ static int process_sysctl_arg(char *param, char *val, return 0; } + if (!val) + return -EINVAL; + /* * To set sysctl options, we use a temporary mount of proc, look up the * respective sys/ file and write to it. To avoid mounting it when no -- 2.27.0
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