| Message ID | 20210118133029.28580-1-nixiaoming@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] proc_sysctl: fix oops caused by incorrect command parameters. | expand |
On 1/18/21 2:30 PM, Xiaoming Ni wrote: > 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") > Cc: stable@kernel.org # v5.8-rc1+ > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Thanks! > > --------- > v4: According to Vlastimil Babka's recommendations > add check len == 0, and cc stable > v3: https://lore.kernel.org/lkml/20210112033155.91502-1-nixiaoming@huawei.com/ > 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 | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c > index 317899222d7f..d2018f70d1fa 100644 > --- a/fs/proc/proc_sysctl.c > +++ b/fs/proc/proc_sysctl.c > @@ -1770,6 +1770,12 @@ static int process_sysctl_arg(char *param, char *val, > 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 *param, char *val, > file, param, val); > goto out; > } > - len = strlen(val); > wret = kernel_write(file, val, len, &pos); > if (wret < 0) { > err = wret; >
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 317899222d7f..d2018f70d1fa 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -1770,6 +1770,12 @@ static int process_sysctl_arg(char *param, char *val, 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 *param, char *val, file, param, val); goto out; } - len = strlen(val); wret = kernel_write(file, val, len, &pos); if (wret < 0) { err = wret;
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") Cc: stable@kernel.org # v5.8-rc1+ Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> --------- v4: According to Vlastimil Babka's recommendations add check len == 0, and cc stable v3: https://lore.kernel.org/lkml/20210112033155.91502-1-nixiaoming@huawei.com/ 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 | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)