| Message ID | 20220216164223.55546-1-tcs.kernel@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | scsi: add __GFP_ZERO flag for blk_rq_map_kern in function sg_scsi_ioctl | expand |
On Thu, 2022-02-17 at 00:42 +0800, Haimin Zhang wrote: > Add __GFP_ZERO flag for blk_rq_map_kern in function sg_scsi_ioctl to > avoid a kernel information leak issue. This issue can cause the content of > local variable buffer which was passed to function blk_rq_map_kern was > rewritten. At last, it can be leaked to the user buffer. > > Reported-by: TCS Robot <tcs_robot@tencent.com> > Signed-off-by: Haimin Zhang <tcs.kernel@gmail.com> > --- > This can cause a kernel-info-leak problem. > 0. This problem occurred in function scsi_ioctl. If the parameter cmd is SCSI_IOCTL_SEND_COMMAND, the function scsi_ioctl will call sg_scsi_ioctl to further process. > 1. In function sg_scsi_ioctl, it creates a scsi request and calls blk_rq_map_kern to map kernel data to a request. > 3. blq_rq_map_kern calls bio_copy_kern to request a bio. > 4. bio_copy_kern calls alloc_page to request the buffer of a bio. In the case of reading, it wouldn't fill anything into the buffer. > > ``` > __alloc_pages+0xbbf/0x1090 build/../mm/page_alloc.c:5409 > alloc_pages+0x8a5/0xb80 > bio_copy_kern build/../block/blk-map.c:449 [inline] > blk_rq_map_kern+0x813/0x1400 build/../block/blk-map.c:640 > sg_scsi_ioctl build/../drivers/scsi/scsi_ioctl.c:618 [inline] > scsi_ioctl+0x40c0/0x4600 build/../drivers/scsi/scsi_ioctl.c:932 > sg_ioctl_common build/../drivers/scsi/sg.c:1112 [inline] > sg_ioctl+0x3351/0x4c10 build/../drivers/scsi/sg.c:1165 > vfs_ioctl build/../fs/ioctl.c:51 [inline] > __do_sys_ioctl build/../fs/ioctl.c:874 [inline] > __se_sys_ioctl+0x2df/0x4a0 build/../fs/ioctl.c:860 > __x64_sys_ioctl+0xd8/0x110 build/../fs/ioctl.c:860 > do_syscall_x64 build/../arch/x86/entry/common.c:51 [inline] > do_syscall_64+0x54/0xd0 build/../arch/x86/entry/common.c:82 > entry_SYSCALL_64_after_hwframe+0x44/0xae > ``` > > 5. Then this request will be sent to the disk driver. When bio is finished, bio_copy_kern_endio_read will copy the readed content back to parameter data from the bio. > But if the block driver didn't process this request, the buffer of bio is still unitialized. > > ``` > memcpy_from_page build/../include/linux/highmem.h:346 [inline] > memcpy_from_bvec build/../include/linux/bvec.h:207 [inline] > bio_copy_kern_endio_read+0x4a3/0x620 build/../block/blk-map.c:403 > bio_endio+0xa7f/0xac0 build/../block/bio.c:1491 > req_bio_endio build/../block/blk-mq.c:674 [inline] > blk_update_request+0x1129/0x22d0 build/../block/blk-mq.c:742 > scsi_end_request+0x119/0xe40 build/../drivers/scsi/scsi_lib.c:543 > scsi_io_completion+0x329/0x810 build/../drivers/scsi/scsi_lib.c:939 > scsi_finish_command+0x6e3/0x700 build/../drivers/scsi/scsi.c:199 > scsi_complete+0x239/0x640 build/../drivers/scsi/scsi_lib.c:1441 > blk_complete_reqs build/../block/blk-mq.c:892 [inline] > blk_done_softirq+0x189/0x260 build/../block/blk-mq.c:897 > __do_softirq+0x1ee/0x7c5 build/../kernel/softirq.c:558 > ``` > > 6. Finally, the internal buffer's content is copied to the user buffer which is specified by the parameter sic->data of sg_scsi_ioctl. > _copy_to_user+0x1c9/0x270 build/../lib/usercopy.c:33 > copy_to_user build/../include/linux/uaccess.h:209 [inline] > sg_scsi_ioctl build/../drivers/scsi/scsi_ioctl.c:634 [inline] > scsi_ioctl+0x44d9/0x4600 build/../drivers/scsi/scsi_ioctl.c:932 > sg_ioctl_common build/../drivers/scsi/sg.c:1112 [inline] > sg_ioctl+0x3351/0x4c10 build/../drivers/scsi/sg.c:1165 > vfs_ioctl build/../fs/ioctl.c:51 [inline] > __do_sys_ioctl build/../fs/ioctl.c:874 [inline] > __se_sys_ioctl+0x2df/0x4a0 build/../fs/ioctl.c:860 > __x64_sys_ioctl+0xd8/0x110 build/../fs/ioctl.c:860 > do_syscall_x64 build/../arch/x86/entry/common.c:51 [inline] > do_syscall_64+0x54/0xd0 build/../arch/x86/entry/common.c:82 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > drivers/scsi/scsi_ioctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi_ioctl.c b/drivers/scsi/scsi_ioctl.c > index e13fd380deb6..e92836f4bbd6 100644 > --- a/drivers/scsi/scsi_ioctl.c > +++ b/drivers/scsi/scsi_ioctl.c > @@ -607,7 +607,7 @@ static int sg_scsi_ioctl(struct request_queue *q, fmode_t mode, > } > > if (bytes) { > - err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO); > + err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO | __GFP_ZERO); > if (err) > goto error; > } Reviewed-by: Ewan D. Milne <emilne@redhat.com>
diff --git a/drivers/scsi/scsi_ioctl.c b/drivers/scsi/scsi_ioctl.c index e13fd380deb6..e92836f4bbd6 100644 --- a/drivers/scsi/scsi_ioctl.c +++ b/drivers/scsi/scsi_ioctl.c @@ -607,7 +607,7 @@ static int sg_scsi_ioctl(struct request_queue *q, fmode_t mode, } if (bytes) { - err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO); + err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO | __GFP_ZERO); if (err) goto error; }
Add __GFP_ZERO flag for blk_rq_map_kern in function sg_scsi_ioctl to avoid a kernel information leak issue. This issue can cause the content of local variable buffer which was passed to function blk_rq_map_kern was rewritten. At last, it can be leaked to the user buffer. Reported-by: TCS Robot <tcs_robot@tencent.com> Signed-off-by: Haimin Zhang <tcs.kernel@gmail.com> --- This can cause a kernel-info-leak problem. 0. This problem occurred in function scsi_ioctl. If the parameter cmd is SCSI_IOCTL_SEND_COMMAND, the function scsi_ioctl will call sg_scsi_ioctl to further process. 1. In function sg_scsi_ioctl, it creates a scsi request and calls blk_rq_map_kern to map kernel data to a request. 3. blq_rq_map_kern calls bio_copy_kern to request a bio. 4. bio_copy_kern calls alloc_page to request the buffer of a bio. In the case of reading, it wouldn't fill anything into the buffer. ``` __alloc_pages+0xbbf/0x1090 build/../mm/page_alloc.c:5409 alloc_pages+0x8a5/0xb80 bio_copy_kern build/../block/blk-map.c:449 [inline] blk_rq_map_kern+0x813/0x1400 build/../block/blk-map.c:640 sg_scsi_ioctl build/../drivers/scsi/scsi_ioctl.c:618 [inline] scsi_ioctl+0x40c0/0x4600 build/../drivers/scsi/scsi_ioctl.c:932 sg_ioctl_common build/../drivers/scsi/sg.c:1112 [inline] sg_ioctl+0x3351/0x4c10 build/../drivers/scsi/sg.c:1165 vfs_ioctl build/../fs/ioctl.c:51 [inline] __do_sys_ioctl build/../fs/ioctl.c:874 [inline] __se_sys_ioctl+0x2df/0x4a0 build/../fs/ioctl.c:860 __x64_sys_ioctl+0xd8/0x110 build/../fs/ioctl.c:860 do_syscall_x64 build/../arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 build/../arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae ``` 5. Then this request will be sent to the disk driver. When bio is finished, bio_copy_kern_endio_read will copy the readed content back to parameter data from the bio. But if the block driver didn't process this request, the buffer of bio is still unitialized. ``` memcpy_from_page build/../include/linux/highmem.h:346 [inline] memcpy_from_bvec build/../include/linux/bvec.h:207 [inline] bio_copy_kern_endio_read+0x4a3/0x620 build/../block/blk-map.c:403 bio_endio+0xa7f/0xac0 build/../block/bio.c:1491 req_bio_endio build/../block/blk-mq.c:674 [inline] blk_update_request+0x1129/0x22d0 build/../block/blk-mq.c:742 scsi_end_request+0x119/0xe40 build/../drivers/scsi/scsi_lib.c:543 scsi_io_completion+0x329/0x810 build/../drivers/scsi/scsi_lib.c:939 scsi_finish_command+0x6e3/0x700 build/../drivers/scsi/scsi.c:199 scsi_complete+0x239/0x640 build/../drivers/scsi/scsi_lib.c:1441 blk_complete_reqs build/../block/blk-mq.c:892 [inline] blk_done_softirq+0x189/0x260 build/../block/blk-mq.c:897 __do_softirq+0x1ee/0x7c5 build/../kernel/softirq.c:558 ``` 6. Finally, the internal buffer's content is copied to the user buffer which is specified by the parameter sic->data of sg_scsi_ioctl. _copy_to_user+0x1c9/0x270 build/../lib/usercopy.c:33 copy_to_user build/../include/linux/uaccess.h:209 [inline] sg_scsi_ioctl build/../drivers/scsi/scsi_ioctl.c:634 [inline] scsi_ioctl+0x44d9/0x4600 build/../drivers/scsi/scsi_ioctl.c:932 sg_ioctl_common build/../drivers/scsi/sg.c:1112 [inline] sg_ioctl+0x3351/0x4c10 build/../drivers/scsi/sg.c:1165 vfs_ioctl build/../fs/ioctl.c:51 [inline] __do_sys_ioctl build/../fs/ioctl.c:874 [inline] __se_sys_ioctl+0x2df/0x4a0 build/../fs/ioctl.c:860 __x64_sys_ioctl+0xd8/0x110 build/../fs/ioctl.c:860 do_syscall_x64 build/../arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 build/../arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae drivers/scsi/scsi_ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)