Re: [PATCH] scsi: prevent stack buffer overflow in host_reset
On Thu, 2012-11-15 at 15:51 -0500, Sasha Levin wrote:
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index ce5224c..77ba946 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -249,9 +249,9 @@ static DEVICE_ATTR(active_mode, S_IRUGO | S_IWUSR,
> show_shost_active_mode, NULL)
>
> static int check_reset_type(char *str)
> {
> - if (strncmp(str, "adapter", 10) == 0)
> + if (sysfs_streq(str, "adapter"))
> return SCSI_ADAPTER_RESET;
> - else if (strncmp(str, "firmware", 10) == 0)
> + else if (sysfs_streq(str, "firmware"))
> return SCSI_FIRMWARE_RESET;
> else
> return 0;
> @@ -264,12 +264,9 @@ store_host_reset(struct device *dev, struct
> device_attribute *attr,
> struct Scsi_Host *shost = class_to_shost(dev);
> struct scsi_host_template *sht = shost->hostt;
> int ret = -EINVAL;
> - char str[10];
> int type;
>
> - sscanf(buf, "%s", str);
> - type = check_reset_type(str);
> -
> + type = check_reset_type(buf);
> if (!type)
> goto exit_store_host_reset;
You didn't compile test this:
CC [M] drivers/scsi/scsi_sysfs.o
drivers/scsi/scsi_sysfs.c: In function ‘store_host_reset’:
drivers/scsi/scsi_sysfs.c:269:2: warning: passing argument 1 of
‘check_reset_type’ discards ‘const’ qualifier from pointer target type [enabled
by default]
drivers/scsi/scsi_sysfs.c:250:12: note: expected ‘char *’ but argument is of
type ‘const char *’
It needs a const in check_reset_type().
I've added it.
James
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Re: [PATCH] scsi: prevent stack buffer overflow in host_reset
Am Donnerstag 15 November 2012, 15:51:46 schrieb Sasha Levin:
> store_host_reset() has tried to re-invent the wheel to compare sysfs
> strings. Unfortunately it did so poorly and never bothered to check the
> input from userspace before overwriting stack with it, so something simple
> as:
>
> echo "WoopsieWoopsie" >
> /sys/devices/pseudo_0/adapter0/host0/scsi_host/host0/host_reset
>
> would result in:
>
> [ 316.310101] Kernel panic - not syncing: stack-protector: Kernel stack is
> corrupted in: 81f5bac7 [ 316.310101]
> [ 316.320051] Pid: 6655, comm: sh Tainted: GW
> 3.7.0-rc5-next-20121114-sasha-00016-g5c9d68d-dirty #129 [ 316.320051] Call
> Trace:
> [ 316.340058] pps pps0: PPS event at 1352918752.620355751
> [ 316.340062] pps pps0: capture assert seq #303
> [ 316.320051] [] panic+0xcd/0x1f4
> [ 316.320051] [] ? store_host_reset+0xd7/0x100
> [ 316.320051] [] __stack_chk_fail+0x16/0x20
> [ 316.320051] [] store_host_reset+0xd7/0x100
> [ 316.320051] [] dev_attr_store+0x13/0x30
> [ 316.320051] [] sysfs_write_file+0x101/0x170
> [ 316.320051] [] vfs_write+0xb8/0x180
> [ 316.320051] [] sys_write+0x50/0xa0
> [ 316.320051] [] tracesys+0xe1/0xe6
>
> Fix this by uninventing whatever was going on there and just use
> sysfs_streq.
>
> Bug introduced by 29443691 ("[SCSI] scsi: Added support for adapter and
> firmware reset").
>
> Signed-off-by: Sasha Levin
That revision is in 3.2 and all following, so I think this needs to go into
stable, too.
Eike
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