| Message ID | 342ee238-0e7c-c213-eecc-7062f24985cc@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | brd: check parameter validation before register_blkdev func | expand |
Friendly ping... On 2020/1/10 13:10, Zhiqiang Liu wrote: > > In brd_init func, rd_nr num of brd_device are firstly allocated > and add in brd_devices, then brd_devices are traversed to add each > brd_device by calling add_disk func. When allocating brd_device, > the disk->first_minor is set to i * max_part, if rd_nr * max_part > is larger than MINORMASK, two different brd_device may have the same > devt, then only one of them can be successfully added. > when rmmod brd.ko, it will cause oops when calling brd_exit. > > Follow those steps: > # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 > # rmmod brd > then, the oops will appear. > > Oops log: > [ 726.613722] Call trace: > [ 726.614175] kernfs_find_ns+0x24/0x130 > [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 > [ 726.615749] sysfs_remove_group+0x38/0xb0 > [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 > [ 726.617320] blk_unregister_queue+0x98/0x100 > [ 726.618105] del_gendisk+0x144/0x2b8 > [ 726.618759] brd_exit+0x68/0x560 [brd] > [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 > [ 726.620384] el0_svc_common+0x78/0x130 > [ 726.621057] el0_svc_handler+0x38/0x78 > [ 726.621738] el0_svc+0x8/0xc > [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) > > Here, we add brd_check_par_valid func to check parameter > validation before register_blkdev func. > > Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> > --- > drivers/block/brd.c | 33 ++++++++++++++++++++++++++------- > 1 file changed, 26 insertions(+), 7 deletions(-) > > diff --git a/drivers/block/brd.c b/drivers/block/brd.c > index df8103dd40ac..3a4510b2c24f 100644 > --- a/drivers/block/brd.c > +++ b/drivers/block/brd.c > @@ -330,16 +330,16 @@ static const struct block_device_operations brd_fops = { > /* > * And now the modules code and kernel interface. > */ > -static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; > -module_param(rd_nr, int, 0444); > +static unsigned int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; > +module_param(rd_nr, uint, 0444); > MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); > > unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE; > module_param(rd_size, ulong, 0444); > MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); > > -static int max_part = 1; > -module_param(max_part, int, 0444); > +static unsigned int max_part = 1; > +module_param(max_part, uint, 0444); > MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); > > MODULE_LICENSE("GPL"); > @@ -468,10 +468,25 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) > return kobj; > } > > +static inline int brd_check_par_valid(void) > +{ > + if (unlikely(!rd_nr)) > + rd_nr = 1; > + > + if (unlikely(!max_part)) > + max_part = 1; > + > + if (rd_nr * max_part > MINORMASK) > + return -EINVAL; > + > + return 0; > + > +} > + > static int __init brd_init(void) > { > struct brd_device *brd, *next; > - int i; > + int i, ret; > > /* > * brd module now has a feature to instantiate underlying device > @@ -488,11 +503,15 @@ static int __init brd_init(void) > * dynamically. > */ > > + ret = brd_check_par_valid(); > + if (ret) { > + pr_info("brd: invalid parameter setting!!!\n"); > + return ret; > + } > + > if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) > return -EIO; > > - if (unlikely(!max_part)) > - max_part = 1; > > for (i = 0; i < rd_nr; i++) { > brd = brd_alloc(i); >
On Fri, Jan 10, 2020 at 01:10:20PM +0800, Zhiqiang Liu wrote: > > In brd_init func, rd_nr num of brd_device are firstly allocated > and add in brd_devices, then brd_devices are traversed to add each > brd_device by calling add_disk func. When allocating brd_device, > the disk->first_minor is set to i * max_part, if rd_nr * max_part > is larger than MINORMASK, two different brd_device may have the same > devt, then only one of them can be successfully added. > when rmmod brd.ko, it will cause oops when calling brd_exit. > > Follow those steps: > # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 > # rmmod brd > then, the oops will appear. > > Oops log: > [ 726.613722] Call trace: > [ 726.614175] kernfs_find_ns+0x24/0x130 > [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 > [ 726.615749] sysfs_remove_group+0x38/0xb0 > [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 > [ 726.617320] blk_unregister_queue+0x98/0x100 > [ 726.618105] del_gendisk+0x144/0x2b8 > [ 726.618759] brd_exit+0x68/0x560 [brd] > [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 > [ 726.620384] el0_svc_common+0x78/0x130 > [ 726.621057] el0_svc_handler+0x38/0x78 > [ 726.621738] el0_svc+0x8/0xc > [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) > > Here, we add brd_check_par_valid func to check parameter > validation before register_blkdev func. > > Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> > --- > drivers/block/brd.c | 33 ++++++++++++++++++++++++++------- > 1 file changed, 26 insertions(+), 7 deletions(-) > > diff --git a/drivers/block/brd.c b/drivers/block/brd.c > index df8103dd40ac..3a4510b2c24f 100644 > --- a/drivers/block/brd.c > +++ b/drivers/block/brd.c > @@ -330,16 +330,16 @@ static const struct block_device_operations brd_fops = { > /* > * And now the modules code and kernel interface. > */ > -static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; > -module_param(rd_nr, int, 0444); > +static unsigned int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; > +module_param(rd_nr, uint, 0444); > MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); > > unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE; > module_param(rd_size, ulong, 0444); > MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); > > -static int max_part = 1; > -module_param(max_part, int, 0444); > +static unsigned int max_part = 1; > +module_param(max_part, uint, 0444); > MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); > > MODULE_LICENSE("GPL"); > @@ -468,10 +468,25 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) > return kobj; > } > > +static inline int brd_check_par_valid(void) > +{ > + if (unlikely(!rd_nr)) > + rd_nr = 1; > + > + if (unlikely(!max_part)) > + max_part = 1; > + > + if (rd_nr * max_part > MINORMASK) > + return -EINVAL; > + > + return 0; > + > +} > + > static int __init brd_init(void) > { > struct brd_device *brd, *next; > - int i; > + int i, ret; > > /* > * brd module now has a feature to instantiate underlying device > @@ -488,11 +503,15 @@ static int __init brd_init(void) > * dynamically. > */ > > + ret = brd_check_par_valid(); > + if (ret) { > + pr_info("brd: invalid parameter setting!!!\n"); > + return ret; > + } > + The max supported partition number is 256, see __alloc_disk_node(). So even though one bigger number is passed to alloc_disk(), at most 256 partitions are allowed on that disk. Maybe you can apply the following way to avoid the issue: disk->first_minor = i * disk->minors; However, looks 'rd_nr' still needs to be validated(rd_nr < 2 ^ 23). Thanks, Ming
On 2020/1/13 19:04, Ming Lei wrote: > On Fri, Jan 10, 2020 at 01:10:20PM +0800, Zhiqiang Liu wrote: >> >> In brd_init func, rd_nr num of brd_device are firstly allocated >> and add in brd_devices, then brd_devices are traversed to add each >> brd_device by calling add_disk func. When allocating brd_device, >> the disk->first_minor is set to i * max_part, if rd_nr * max_part >> is larger than MINORMASK, two different brd_device may have the same >> devt, then only one of them can be successfully added. >> when rmmod brd.ko, it will cause oops when calling brd_exit. >> >> Follow those steps: >> # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 >> # rmmod brd >> then, the oops will appear. >> >> Oops log: >> [ 726.613722] Call trace: >> [ 726.614175] kernfs_find_ns+0x24/0x130 >> [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 >> [ 726.615749] sysfs_remove_group+0x38/0xb0 >> [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 >> [ 726.617320] blk_unregister_queue+0x98/0x100 >> [ 726.618105] del_gendisk+0x144/0x2b8 >> [ 726.618759] brd_exit+0x68/0x560 [brd] >> [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 >> [ 726.620384] el0_svc_common+0x78/0x130 >> [ 726.621057] el0_svc_handler+0x38/0x78 >> [ 726.621738] el0_svc+0x8/0xc >> [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) >> >> Here, we add brd_check_par_valid func to check parameter >> validation before register_blkdev func. >> >> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> >> --- >> drivers/block/brd.c | 33 ++++++++++++++++++++++++++------- >> +static inline int brd_check_par_valid(void) >> +{ >> + if (unlikely(!rd_nr)) >> + rd_nr = 1; >> + >> + if (unlikely(!max_part)) >> + max_part = 1; >> + >> + if (rd_nr * max_part > MINORMASK) >> + return -EINVAL; >> + >> + return 0; >> + >> +} >> + >> static int __init brd_init(void) >> { >> struct brd_device *brd, *next; >> - int i; >> + int i, ret; >> >> /* >> * brd module now has a feature to instantiate underlying device >> @@ -488,11 +503,15 @@ static int __init brd_init(void) >> * dynamically. >> */ >> >> + ret = brd_check_par_valid(); >> + if (ret) { >> + pr_info("brd: invalid parameter setting!!!\n"); >> + return ret; >> + } >> + > > The max supported partition number is 256, see __alloc_disk_node(). > So even though one bigger number is passed to alloc_disk(), at most > 256 partitions are allowed on that disk. Maybe you can apply the > following way to avoid the issue: > > disk->first_minor = i * disk->minors; > > However, looks 'rd_nr' still needs to be validated(rd_nr < 2 ^ 23). > Thanks for your reply. As you said, minors is limited to DISK_MAX_PARTS in __alloc_disk_node when calling alloc_disk in brd_alloc func. We can set: disk->first_minor = i * disk->minors as your suggestion. As for 'rd_nr', I think we should make sure that 'disk->first_minor' should be not larger than MINORMASK. ->add_disk ->device_add_disk ->__device_add_disk ->blk_alloc_devt ->MKDEV If rd_nr > MINORMASK / min(max_part, DISK_MAX_PARTS), two different brd_device may have the same devt by calling MKDEV in blk_alloc_devt func. For example, MKDEV(1, 0) is equal to MKDEV(1, MINORMASK + 1). So we should check both rd_nr and max_part as follows, static inline int brd_check_par_valid(void) { if (unlikely(!rd_nr)) rd_nr = 1; if (unlikely(!max_part)) max_part = 1; if (max_part > DISK_MAX_PARTS) max_part = DISK_MAX_PARTS; if (rd_nr > MINORMASK / max_part) return -EINVAL; return 0; } I will send the v2 patch.
diff --git a/drivers/block/brd.c b/drivers/block/brd.c index df8103dd40ac..3a4510b2c24f 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -330,16 +330,16 @@ static const struct block_device_operations brd_fops = { /* * And now the modules code and kernel interface. */ -static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; -module_param(rd_nr, int, 0444); +static unsigned int rd_nr = CONFIG_BLK_DEV_RAM_COUNT; +module_param(rd_nr, uint, 0444); MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE; module_param(rd_size, ulong, 0444); MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); -static int max_part = 1; -module_param(max_part, int, 0444); +static unsigned int max_part = 1; +module_param(max_part, uint, 0444); MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); MODULE_LICENSE("GPL"); @@ -468,10 +468,25 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data) return kobj; } +static inline int brd_check_par_valid(void) +{ + if (unlikely(!rd_nr)) + rd_nr = 1; + + if (unlikely(!max_part)) + max_part = 1; + + if (rd_nr * max_part > MINORMASK) + return -EINVAL; + + return 0; + +} + static int __init brd_init(void) { struct brd_device *brd, *next; - int i; + int i, ret; /* * brd module now has a feature to instantiate underlying device @@ -488,11 +503,15 @@ static int __init brd_init(void) * dynamically. */ + ret = brd_check_par_valid(); + if (ret) { + pr_info("brd: invalid parameter setting!!!\n"); + return ret; + } + if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) return -EIO; - if (unlikely(!max_part)) - max_part = 1; for (i = 0; i < rd_nr; i++) { brd = brd_alloc(i);
In brd_init func, rd_nr num of brd_device are firstly allocated and add in brd_devices, then brd_devices are traversed to add each brd_device by calling add_disk func. When allocating brd_device, the disk->first_minor is set to i * max_part, if rd_nr * max_part is larger than MINORMASK, two different brd_device may have the same devt, then only one of them can be successfully added. when rmmod brd.ko, it will cause oops when calling brd_exit. Follow those steps: # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576 # rmmod brd then, the oops will appear. Oops log: [ 726.613722] Call trace: [ 726.614175] kernfs_find_ns+0x24/0x130 [ 726.614852] kernfs_find_and_get_ns+0x44/0x68 [ 726.615749] sysfs_remove_group+0x38/0xb0 [ 726.616520] blk_trace_remove_sysfs+0x1c/0x28 [ 726.617320] blk_unregister_queue+0x98/0x100 [ 726.618105] del_gendisk+0x144/0x2b8 [ 726.618759] brd_exit+0x68/0x560 [brd] [ 726.619501] __arm64_sys_delete_module+0x19c/0x2a0 [ 726.620384] el0_svc_common+0x78/0x130 [ 726.621057] el0_svc_handler+0x38/0x78 [ 726.621738] el0_svc+0x8/0xc [ 726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260) Here, we add brd_check_par_valid func to check parameter validation before register_blkdev func. Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> --- drivers/block/brd.c | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-)