diff options
| author | Martin Schwidefsky | 2016-04-25 17:54:28 +0200 |
|---|---|---|
| committer | Martin Schwidefsky | 2016-04-27 09:33:39 +0200 |
| commit | 532c34b5fbf1687df63b3fcd5b2846312ac943c6 (patch) | |
| tree | 3bc98a98c96a419d250e46dc7b0426b73ed65d58 /drivers/s390 | |
| parent | 723cacbd9dc79582e562c123a0bacf8bfc69e72a (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')
| -rw-r--r-- | drivers/s390/char/sclp_ctl.c | 12 |
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); |