From: Sasha Levin Date: Thu, 15 Nov 2012 20:51:46 +0000 (-0500) Subject: [SCSI] prevent stack buffer overflow in host_reset X-Git-Tag: v3.8-rc1~116^2~35 X-Git-Url: http://pileus.org/git/?p=~andy%2Flinux;a=commitdiff_plain;h=072f19b4bea31cdd482d79f805413f2f9ac9e233 [SCSI] prevent stack buffer overflow in host_reset 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: ffffffff81f5bac7 [ 316.310101] [ 316.320051] Pid: 6655, comm: sh Tainted: G W 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"). [jejb: added necessary const to prevent compile warnings] Signed-off-by: Sasha Levin Cc: #3.2+ Signed-off-by: James Bottomley --- diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index ce5224c92ed..931a7d95420 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -247,11 +247,11 @@ show_shost_active_mode(struct device *dev, static DEVICE_ATTR(active_mode, S_IRUGO | S_IWUSR, show_shost_active_mode, NULL); -static int check_reset_type(char *str) +static int check_reset_type(const 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;