* [Internal Review] [Patch] btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()
@ 2025-01-23 11:41 Shubham Pushpkar
2025-01-23 13:08 ` Daniel Walker (danielwa)
0 siblings, 1 reply; 4+ messages in thread
From: Shubham Pushpkar @ 2025-01-23 11:41 UTC (permalink / raw)
To: xe-linux-external; +Cc: Zhihao Cheng, stable, David Sterba, Shubham Pushpkar
From: Zhihao Cheng <chengzhihao1@huawei.com>
commit aec8e6bf839101784f3ef037dcdb9432c3f32343 ("btrfs:
fix use-after-free of block device file in __btrfs_free_extra_devids()")
Mounting btrfs from two images (which have the same one fsid and two
different dev_uuids) in certain executing order may trigger an UAF for
variable 'device->bdev_file' in __btrfs_free_extra_devids(). And
following are the details:
1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs
devices by ioctl(BTRFS_IOC_SCAN_DEV):
/ btrfs_device_1 → loop0
fs_device
\ btrfs_device_2 → loop1
2. mount /dev/loop0 /mnt
btrfs_open_devices
btrfs_device_1->bdev_file = btrfs_get_bdev_and_sb(loop0)
btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)
btrfs_fill_super
open_ctree
fail: btrfs_close_devices // -ENOMEM
btrfs_close_bdev(btrfs_device_1)
fput(btrfs_device_1->bdev_file)
// btrfs_device_1->bdev_file is freed
btrfs_close_bdev(btrfs_device_2)
fput(btrfs_device_2->bdev_file)
3. mount /dev/loop1 /mnt
btrfs_open_devices
btrfs_get_bdev_and_sb(&bdev_file)
// EIO, btrfs_device_1->bdev_file is not assigned,
// which points to a freed memory area
btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)
btrfs_fill_super
open_ctree
btrfs_free_extra_devids
if (btrfs_device_1->bdev_file)
fput(btrfs_device_1->bdev_file) // UAF !
Fix it by setting 'device->bdev_file' as 'NULL' after closing the
btrfs_device in btrfs_close_one_device().
Fixes: CVE-2024-50217
Fixes: 142388194191 ("btrfs: do not background blkdev_put()")
CC: stable@vger.kernel.org # 4.19+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219408
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
(cherry picked from commit aec8e6bf839101784f3ef037dcdb9432c3f32343)
Signed-off-by: Shubham Pushpkar <spushpka@cisco.com>
---
fs/btrfs/volumes.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b9a0b26d08e1..ab2412542ce5 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1176,6 +1176,7 @@ static void btrfs_close_one_device(struct btrfs_device *device)
if (device->bdev) {
fs_devices->open_devices--;
device->bdev = NULL;
+ device->bdev_file = NULL;
}
clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
btrfs_destroy_dev_zone_info(device);
--
2.35.6
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [Internal Review] [Patch] btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()
2025-01-23 11:41 [Internal Review] [Patch] btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids() Shubham Pushpkar
@ 2025-01-23 13:08 ` Daniel Walker (danielwa)
2025-01-23 13:56 ` Greg KH
0 siblings, 1 reply; 4+ messages in thread
From: Daniel Walker (danielwa) @ 2025-01-23 13:08 UTC (permalink / raw)
To: Shubham Pushpkar -X (spushpka - E INFOCHIPS PRIVATE LIMITED at Cisco)
Cc: xe-linux-external(mailer list), Zhihao Cheng,
stable@vger.kernel.org, David Sterba
Looks fine for release to me.
On Thu, Jan 23, 2025 at 03:41:41AM -0800, Shubham Pushpkar wrote:
> From: Zhihao Cheng <chengzhihao1@huawei.com>
>
> commit aec8e6bf839101784f3ef037dcdb9432c3f32343 ("btrfs:
> fix use-after-free of block device file in __btrfs_free_extra_devids()")
>
> Mounting btrfs from two images (which have the same one fsid and two
> different dev_uuids) in certain executing order may trigger an UAF for
> variable 'device->bdev_file' in __btrfs_free_extra_devids(). And
> following are the details:
>
> 1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs
> devices by ioctl(BTRFS_IOC_SCAN_DEV):
>
> / btrfs_device_1 → loop0
> fs_device
> \ btrfs_device_2 → loop1
> 2. mount /dev/loop0 /mnt
> btrfs_open_devices
> btrfs_device_1->bdev_file = btrfs_get_bdev_and_sb(loop0)
> btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)
> btrfs_fill_super
> open_ctree
> fail: btrfs_close_devices // -ENOMEM
> btrfs_close_bdev(btrfs_device_1)
> fput(btrfs_device_1->bdev_file)
> // btrfs_device_1->bdev_file is freed
> btrfs_close_bdev(btrfs_device_2)
> fput(btrfs_device_2->bdev_file)
>
> 3. mount /dev/loop1 /mnt
> btrfs_open_devices
> btrfs_get_bdev_and_sb(&bdev_file)
> // EIO, btrfs_device_1->bdev_file is not assigned,
> // which points to a freed memory area
> btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)
> btrfs_fill_super
> open_ctree
> btrfs_free_extra_devids
> if (btrfs_device_1->bdev_file)
> fput(btrfs_device_1->bdev_file) // UAF !
>
> Fix it by setting 'device->bdev_file' as 'NULL' after closing the
> btrfs_device in btrfs_close_one_device().
>
> Fixes: CVE-2024-50217
> Fixes: 142388194191 ("btrfs: do not background blkdev_put()")
> CC: stable@vger.kernel.org # 4.19+
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219408
> Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
> Reviewed-by: David Sterba <dsterba@suse.com>
> Signed-off-by: David Sterba <dsterba@suse.com>
> (cherry picked from commit aec8e6bf839101784f3ef037dcdb9432c3f32343)
> Signed-off-by: Shubham Pushpkar <spushpka@cisco.com>
> ---
> fs/btrfs/volumes.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index b9a0b26d08e1..ab2412542ce5 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1176,6 +1176,7 @@ static void btrfs_close_one_device(struct btrfs_device *device)
> if (device->bdev) {
> fs_devices->open_devices--;
> device->bdev = NULL;
> + device->bdev_file = NULL;
> }
> clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
> btrfs_destroy_dev_zone_info(device);
> --
> 2.35.6
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Internal Review] [Patch] btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()
2025-01-23 13:08 ` Daniel Walker (danielwa)
@ 2025-01-23 13:56 ` Greg KH
2025-01-23 14:20 ` Daniel Walker (danielwa)
0 siblings, 1 reply; 4+ messages in thread
From: Greg KH @ 2025-01-23 13:56 UTC (permalink / raw)
To: Daniel Walker (danielwa)
Cc: Shubham Pushpkar -X (spushpka - E INFOCHIPS PRIVATE LIMITED at Cisco),
xe-linux-external(mailer list), Zhihao Cheng,
stable@vger.kernel.org, David Sterba
On Thu, Jan 23, 2025 at 01:08:52PM +0000, Daniel Walker (danielwa) wrote:
>
> Looks fine for release to me.
Released to where? This is already in the 6.12 release, what other
stable tree should it be added to?
confused,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Internal Review] [Patch] btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()
2025-01-23 13:56 ` Greg KH
@ 2025-01-23 14:20 ` Daniel Walker (danielwa)
0 siblings, 0 replies; 4+ messages in thread
From: Daniel Walker (danielwa) @ 2025-01-23 14:20 UTC (permalink / raw)
To: Greg KH
Cc: Shubham Pushpkar -X (spushpka - E INFOCHIPS PRIVATE LIMITED at Cisco),
xe-linux-external(mailer list), Zhihao Cheng,
stable@vger.kernel.org, David Sterba
On Thu, Jan 23, 2025 at 02:56:08PM +0100, Greg KH wrote:
> On Thu, Jan 23, 2025 at 01:08:52PM +0000, Daniel Walker (danielwa) wrote:
> >
> > Looks fine for release to me.
>
> Released to where? This is already in the 6.12 release, what other
> stable tree should it be added to?
>
> confused,
Don't worry, it was suppose to be internal to Ciscp but looks like the CC's were not correct.
Daniel
^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-01-23 11:41 [Internal Review] [Patch] btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids() Shubham Pushpkar
2025-01-23 13:08 ` Daniel Walker (danielwa)
2025-01-23 13:56 ` Greg KH
2025-01-23 14:20 ` Daniel Walker (danielwa)
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