From: Xiaoming Ni <nixiaom...@huawei.com> commit 697edcb0e4eadc41645fe88c991fe6a206b1a08d upstream.
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(). Link: https://lkml.kernel.org/r/20210118133029.28580-1-nixiaom...@huawei.com Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters from kernel command line") Signed-off-by: Xiaoming Ni <nixiaom...@huawei.com> Acked-by: Vlastimil Babka <vba...@suse.cz> Cc: Luis Chamberlain <mcg...@kernel.org> Cc: Kees Cook <keesc...@chromium.org> Cc: Iurii Zaikin <yzai...@google.com> Cc: Alexey Dobriyan <adobri...@gmail.com> Cc: Michal Hocko <mho...@suse.com> Cc: Masami Hiramatsu <mhira...@kernel.org> Cc: Heiner Kallweit <hkallwe...@gmail.com> Cc: Randy Dunlap <rdun...@infradead.org> Cc: <sta...@vger.kernel.org> [5.8+] Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/proc/proc_sysctl.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -1770,6 +1770,12 @@ static int process_sysctl_arg(char *para return 0; } + if (!val) + return -EINVAL; + len = strlen(val); + if (len == 0) + 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 @@ -1811,7 +1817,6 @@ static int process_sysctl_arg(char *para file, param, val); goto out; } - len = strlen(val); wret = kernel_write(file, val, len, &pos); if (wret < 0) { err = wret;