4.4-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 4a8ef6999bce998fa5813023a9a6b56eea329dba ]
Dan Carpenter reported the following:
The patch 52898025cf7d: "[S390] dasd: security and PSF update patch for EMC CKD ioctl" from Mar 8, 2010, leads to the following static checker warning:
drivers/s390/block/dasd_eckd.c:4486 dasd_symm_io() error: using offset into zero size array 'psf_data[]'
drivers/s390/block/dasd_eckd.c 4458 /* Copy parms from caller */ 4459 rc = -EFAULT; 4460 if (copy_from_user(&usrparm, argp, sizeof(usrparm))) ^^^^^^^ The user can specify any "usrparm.psf_data_len". They choose zero by mistake.
4461 goto out; 4462 if (is_compat_task()) { 4463 /* Make sure pointers are sane even on 31 bit. */ 4464 rc = -EINVAL; 4465 if ((usrparm.psf_data >> 32) != 0) 4466 goto out; 4467 if ((usrparm.rssd_result >> 32) != 0) 4468 goto out; 4469 usrparm.psf_data &= 0x7fffffffULL; 4470 usrparm.rssd_result &= 0x7fffffffULL; 4471 } 4472 /* alloc I/O data area */ 4473 psf_data = kzalloc(usrparm.psf_data_len, GFP_KERNEL | GFP_DMA); 4474 rssd_result = kzalloc(usrparm.rssd_result_len, GFP_KERNEL | GFP_DMA); 4475 if (!psf_data || !rssd_result) {
kzalloc() returns a ZERO_SIZE_PTR (0x16).
4476 rc = -ENOMEM; 4477 goto out_free; 4478 } 4479 4480 /* get syscall header from user space */ 4481 rc = -EFAULT; 4482 if (copy_from_user(psf_data, 4483 (void __user *)(unsigned long) usrparm.psf_data, 4484 usrparm.psf_data_len))
That all works great.
4485 goto out_free; 4486 psf0 = psf_data[0]; 4487 psf1 = psf_data[1];
But now we're assuming that "->psf_data_len" was at least 2 bytes.
Fix this by checking the user specified length psf_data_len.
Fixes: 52898025cf7d ("[S390] dasd: security and PSF update patch for EMC CKD ioctl") Reported-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Stefan Haberland sth@linux.ibm.com Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/block/dasd_eckd.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c index dac2f6883e28..80a43074c2f9 100644 --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -4023,6 +4023,14 @@ static int dasd_symm_io(struct dasd_device *device, void __user *argp) usrparm.psf_data &= 0x7fffffffULL; usrparm.rssd_result &= 0x7fffffffULL; } + /* at least 2 bytes are accessed and should be allocated */ + if (usrparm.psf_data_len < 2) { + DBF_DEV_EVENT(DBF_WARNING, device, + "Symmetrix ioctl invalid data length %d", + usrparm.psf_data_len); + rc = -EINVAL; + goto out; + } /* alloc I/O data area */ psf_data = kzalloc(usrparm.psf_data_len, GFP_KERNEL | GFP_DMA); rssd_result = kzalloc(usrparm.rssd_result_len, GFP_KERNEL | GFP_DMA);