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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2016-04-25 17:54:28 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-04-27 09:33:39 +0200
commit532c34b5fbf1687df63b3fcd5b2846312ac943c6 (patch)
tree3bc98a98c96a419d250e46dc7b0426b73ed65d58 /drivers/s390/char
parent723cacbd9dc79582e562c123a0bacf8bfc69e72a (diff)
s390/sclp_ctl: fix potential information leak with /dev/sclp
The sclp_ctl_ioctl_sccb function uses two copy_from_user calls to retrieve the sclp request from user space. The first copy_from_user fetches the length of the request which is stored in the first two bytes of the request. The second copy_from_user gets the complete sclp request, but this copies the length field a second time. A malicious user may have changed the length in the meantime. Reported-by: Pengfei Wang <wpengfeinudt@gmail.com> Reviewed-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/char')
-rw-r--r--drivers/s390/char/sclp_ctl.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/s390/char/sclp_ctl.c b/drivers/s390/char/sclp_ctl.c
index 648cb86afd42..ea607a4a1bdd 100644
--- a/drivers/s390/char/sclp_ctl.c
+++ b/drivers/s390/char/sclp_ctl.c
@@ -56,6 +56,7 @@ static int sclp_ctl_ioctl_sccb(void __user *user_area)
{
struct sclp_ctl_sccb ctl_sccb;
struct sccb_header *sccb;
+ unsigned long copied;
int rc;
if (copy_from_user(&ctl_sccb, user_area, sizeof(ctl_sccb)))
@@ -65,14 +66,15 @@ static int sclp_ctl_ioctl_sccb(void __user *user_area)
sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
if (!sccb)
return -ENOMEM;
- if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sizeof(*sccb))) {
+ copied = PAGE_SIZE -
+ copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), PAGE_SIZE);
+ if (offsetof(struct sccb_header, length) +
+ sizeof(sccb->length) > copied || sccb->length > copied) {
rc = -EFAULT;
goto out_free;
}
- if (sccb->length > PAGE_SIZE || sccb->length < 8)
- return -EINVAL;
- if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sccb->length)) {
- rc = -EFAULT;
+ if (sccb->length < 8) {
+ rc = -EINVAL;
goto out_free;
}
rc = sclp_sync_request(ctl_sccb.cmdw, sccb);