diff options
| author | Deepanshu Kartikey <kartikey406@gmail.com> | 2025-12-17 04:47:12 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-12-17 17:35:22 +0300 |
| commit | a58383fa45c706bda3bf4a1955c3a0327dbec7e7 (patch) | |
| tree | 125d2760c548f9e552a13f97e01dc51586da459a | |
| parent | 67d85b062dcb49af9c903a58842a4ed7281f57b8 (diff) | |
| download | linux-a58383fa45c706bda3bf4a1955c3a0327dbec7e7.tar.xz | |
block: add allocation size check in blkdev_pr_read_keys()
blkdev_pr_read_keys() takes num_keys from userspace and uses it to
calculate the allocation size for keys_info via struct_size(). While
there is a check for SIZE_MAX (integer overflow), there is no upper
bound validation on the allocation size itself.
A malicious or buggy userspace can pass a large num_keys value that
doesn't trigger overflow but still results in an excessive allocation
attempt, causing a warning in the page allocator when the order exceeds
MAX_PAGE_ORDER.
Fix this by introducing PR_KEYS_MAX to limit the number of keys to
a sane value. This makes the SIZE_MAX check redundant, so remove it.
Also switch to kvzalloc/kvfree to handle larger allocations gracefully.
Fixes: 22a1ffea5f80 ("block: add IOC_PR_READ_KEYS ioctl")
Tested-by: syzbot+660d079d90f8a1baf54d@syzkaller.appspotmail.com
Reported-by: syzbot+660d079d90f8a1baf54d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=660d079d90f8a1baf54d
Link: https://lore.kernel.org/all/20251212013510.3576091-1-kartikey406@gmail.com/T/ [v1]
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/ioctl.c | 9 | ||||
| -rw-r--r-- | include/uapi/linux/pr.h | 2 |
2 files changed, 7 insertions, 4 deletions
diff --git a/block/ioctl.c b/block/ioctl.c index 61feed686418..344478348a54 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -442,11 +442,12 @@ static int blkdev_pr_read_keys(struct block_device *bdev, blk_mode_t mode, if (copy_from_user(&read_keys, arg, sizeof(read_keys))) return -EFAULT; - keys_info_len = struct_size(keys_info, keys, read_keys.num_keys); - if (keys_info_len == SIZE_MAX) + if (read_keys.num_keys > PR_KEYS_MAX) return -EINVAL; - keys_info = kzalloc(keys_info_len, GFP_KERNEL); + keys_info_len = struct_size(keys_info, keys, read_keys.num_keys); + + keys_info = kvzalloc(keys_info_len, GFP_KERNEL); if (!keys_info) return -ENOMEM; @@ -473,7 +474,7 @@ static int blkdev_pr_read_keys(struct block_device *bdev, blk_mode_t mode, if (copy_to_user(arg, &read_keys, sizeof(read_keys))) ret = -EFAULT; out: - kfree(keys_info); + kvfree(keys_info); return ret; } diff --git a/include/uapi/linux/pr.h b/include/uapi/linux/pr.h index 847f3051057a..f0ecb1677317 100644 --- a/include/uapi/linux/pr.h +++ b/include/uapi/linux/pr.h @@ -79,4 +79,6 @@ struct pr_read_reservation { #define IOC_PR_READ_KEYS _IOWR('p', 206, struct pr_read_keys) #define IOC_PR_READ_RESERVATION _IOR('p', 207, struct pr_read_reservation) +#define PR_KEYS_MAX (1u << 16) + #endif /* _UAPI_PR_H */ |