[PATCH 5.15 088/124] scsi: sr: Do not leak information in ioctl

Greg Kroah-Hartman
2022-04-26T09:12:42Z

From: Tom Rix <trix@redhat.com>

[ Upstream commit faad6cebded8e0fd902b672f220449b93db479eb ]

sr_ioctl.c uses this pattern:

result = sr_do_ioctl(cd, &cgc);
to-user = buffer[];
kfree(buffer);
return result;

Use of a buffer without checking leaks information. Check result and jump
over the use of buffer if there is an error.

result = sr_do_ioctl(cd, &cgc);
if (result)
goto err;
to-user = buffer[];
err:
kfree(buffer);
return result;

Additionally, initialize the buffer to zero.

This problem can be seen in the 2.4.0 kernel.

Link: https://lore.kernel.org/r/20220411174756.2418435-1-trix@redhat.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/sr_ioctl.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/sr_ioctl.c b/drivers/scsi/sr_ioctl.c
index ddd00efc4882..fbdb5124d7f7 100644
--- a/drivers/scsi/sr_ioctl.c
+++ b/drivers/scsi/sr_ioctl.c
@@ -41,7 +41,7 @@ static int sr_read_tochdr(struct cdrom_device_info *cdi,
int result;
unsigned char *buffer;

- buffer = kmalloc(32, GFP_KERNEL);
+ buffer = kzalloc(32, GFP_KERNEL);
if (!buffer)
return -ENOMEM;

@@ -55,10 +55,13 @@ static int sr_read_tochdr(struct cdrom_device_info *cdi,
cgc.data_direction = DMA_FROM_DEVICE;

result = sr_do_ioctl(cd, &cgc);
+ if (result)
+ goto err;

tochdr->cdth_trk0 = buffer[2];
tochdr->cdth_trk1 = buffer[3];

+err:
kfree(buffer);
return result;
}
@@ -71,7 +74,7 @@ static int sr_read_tocentry(struct cdrom_device_info *cdi,
int result;
unsigned char *buffer;

- buffer = kmalloc(32, GFP_KERNEL);
+ buffer = kzalloc(32, GFP_KERNEL);
if (!buffer)
return -ENOMEM;

@@ -86,6 +89,8 @@ static int sr_read_tocentry(struct cdrom_device_info *cdi,
cgc.data_direction = DMA_FROM_DEVICE;

result = sr_do_ioctl(cd, &cgc);
+ if (result)
+ goto err;

tocentry->cdte_ctrl = buffer[5] & 0xf;
tocentry->cdte_adr = buffer[5] >> 4;
@@ -98,6 +103,7 @@ static int sr_read_tocentry(struct cdrom_device_info *cdi,
tocentry->cdte_addr.lba = (((((buffer[8] << 8) + buffer[9]) << 8)
+ buffer[10]) << 8) + buffer[11];

+err:
kfree(buffer);
return result;
}
@@ -384,7 +390,7 @@ int sr_get_mcn(struct cdrom_device_info *cdi, struct cdrom_mcn *mcn)
{
Scsi_CD *cd = cdi->handle;
struct packet_command cgc;
- char *buffer = kmalloc(32, GFP_KERNEL);
+ char *buffer = kzalloc(32, GFP_KERNEL);
int result;

if (!buffer)
@@ -400,10 +406,13 @@ int sr_get_mcn(struct cdrom_device_info *cdi, struct cdrom_mcn *mcn)
cgc.data_direction = DMA_FROM_DEVICE;
cgc.timeout = IOCTL_TIMEOUT;
result = sr_do_ioctl(cd, &cgc);
+ if (result)
+ goto err;

memcpy(mcn->medium_catalog_number, buffer + 9, 13);
mcn->medium_catalog_number[13] = 0;

+err:
kfree(buffer);
return result;
}
--
2.35.1