From: Justin Stitt justinstitt@google.com
[ Upstream commit 9fad9d560af5c654bb38e0b07ee54a4e9acdc5cd ]
Running syzkaller with the newly reintroduced signed integer overflow sanitizer produces this report:
[ 65.194362] ------------[ cut here ]------------ [ 65.197752] UBSAN: signed-integer-overflow in ../drivers/scsi/sr_ioctl.c:436:9 [ 65.203607] -2147483648 * 177 cannot be represented in type 'int' [ 65.207911] CPU: 2 PID: 10416 Comm: syz-executor.1 Not tainted 6.8.0-rc2-00035-gb3ef86b5a957 #1 [ 65.213585] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 65.219923] Call Trace: [ 65.221556] <TASK> [ 65.223029] dump_stack_lvl+0x93/0xd0 [ 65.225573] handle_overflow+0x171/0x1b0 [ 65.228219] sr_select_speed+0xeb/0xf0 [ 65.230786] ? __pm_runtime_resume+0xe6/0x130 [ 65.233606] sr_block_ioctl+0x15d/0x1d0 ...
Historically, the signed integer overflow sanitizer did not work in the kernel due to its interaction with `-fwrapv` but this has since been changed [1] in the newest version of Clang. It was re-enabled in the kernel with Commit 557f8c582a9b ("ubsan: Reintroduce signed overflow sanitizer").
Firstly, let's change the type of "speed" to unsigned long as sr_select_speed()'s only caller passes in an unsigned long anyways.
$ git grep '.select_speed' | drivers/scsi/sr.c: .select_speed = sr_select_speed, ... | static int cdrom_ioctl_select_speed(struct cdrom_device_info *cdi, | unsigned long arg) | { | ... | return cdi->ops->select_speed(cdi, arg); | }
Next, let's add an extra check to make sure we don't exceed 0xffff/177 (350) since 0xffff is the max speed. This has two benefits: 1) we deal with integer overflow before it happens and 2) we properly respect the max speed of 0xffff. There are some "magic" numbers here but I did not want to change more than what was necessary.
Link: https://github.com/llvm/llvm-project/pull/82432 [1] Closes: https://github.com/KSPP/linux/issues/357 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt justinstitt@google.com Link: https://lore.kernel.org/r/20240508-b4-b4-sio-sr_select_speed-v2-1-00b68f7242... Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/cdrom/cdrom-standard.rst | 4 ++-- drivers/scsi/sr.h | 2 +- drivers/scsi/sr_ioctl.c | 5 ++++- include/linux/cdrom.h | 2 +- 4 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/Documentation/cdrom/cdrom-standard.rst b/Documentation/cdrom/cdrom-standard.rst index 7964fe134277b..6c1303cff159e 100644 --- a/Documentation/cdrom/cdrom-standard.rst +++ b/Documentation/cdrom/cdrom-standard.rst @@ -217,7 +217,7 @@ current *struct* is:: int (*media_changed)(struct cdrom_device_info *, int); int (*tray_move)(struct cdrom_device_info *, int); int (*lock_door)(struct cdrom_device_info *, int); - int (*select_speed)(struct cdrom_device_info *, int); + int (*select_speed)(struct cdrom_device_info *, unsigned long); int (*get_last_session) (struct cdrom_device_info *, struct cdrom_multisession *); int (*get_mcn)(struct cdrom_device_info *, struct cdrom_mcn *); @@ -396,7 +396,7 @@ action need be taken, and the return value should be 0.
::
- int select_speed(struct cdrom_device_info *cdi, int speed) + int select_speed(struct cdrom_device_info *cdi, unsigned long speed)
Some CD-ROM drives are capable of changing their head-speed. There are several reasons for changing the speed of a CD-ROM drive. Badly diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h index 1175f2e213b56..dc899277b3a44 100644 --- a/drivers/scsi/sr.h +++ b/drivers/scsi/sr.h @@ -65,7 +65,7 @@ int sr_disk_status(struct cdrom_device_info *); int sr_get_last_session(struct cdrom_device_info *, struct cdrom_multisession *); int sr_get_mcn(struct cdrom_device_info *, struct cdrom_mcn *); int sr_reset(struct cdrom_device_info *); -int sr_select_speed(struct cdrom_device_info *cdi, int speed); +int sr_select_speed(struct cdrom_device_info *cdi, unsigned long speed); int sr_audio_ioctl(struct cdrom_device_info *, unsigned int, void *);
int sr_is_xa(Scsi_CD *); diff --git a/drivers/scsi/sr_ioctl.c b/drivers/scsi/sr_ioctl.c index 5b0b35e60e61f..a0d2556a27bba 100644 --- a/drivers/scsi/sr_ioctl.c +++ b/drivers/scsi/sr_ioctl.c @@ -425,11 +425,14 @@ int sr_reset(struct cdrom_device_info *cdi) return 0; }
-int sr_select_speed(struct cdrom_device_info *cdi, int speed) +int sr_select_speed(struct cdrom_device_info *cdi, unsigned long speed) { Scsi_CD *cd = cdi->handle; struct packet_command cgc;
+ /* avoid exceeding the max speed or overflowing integer bounds */ + speed = clamp(0, speed, 0xffff / 177); + if (speed == 0) speed = 0xffff; /* set to max */ else diff --git a/include/linux/cdrom.h b/include/linux/cdrom.h index 98c6fd0b39b63..fdfb61ccf55ae 100644 --- a/include/linux/cdrom.h +++ b/include/linux/cdrom.h @@ -77,7 +77,7 @@ struct cdrom_device_ops { unsigned int clearing, int slot); int (*tray_move) (struct cdrom_device_info *, int); int (*lock_door) (struct cdrom_device_info *, int); - int (*select_speed) (struct cdrom_device_info *, int); + int (*select_speed) (struct cdrom_device_info *, unsigned long); int (*get_last_session) (struct cdrom_device_info *, struct cdrom_multisession *); int (*get_mcn) (struct cdrom_device_info *,