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([2405:201:682f:389d:8924:b5f2:ed79:957e]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29ee9b376e2sm36857985ad.14.2025.12.11.17.35.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Dec 2025 17:35:17 -0800 (PST) From: Deepanshu Kartikey To: axboe@kernel.dk, stefanha@redhat.com, martin.petersen@oracle.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+660d079d90f8a1baf54d@syzkaller.appspotmail.com Subject: [PATCH] block: add allocation size check in blkdev_pr_read_keys() Date: Fri, 12 Dec 2025 07:05:10 +0530 Message-ID: <20251212013510.3576091-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 checking that keys_info_len does not exceed KMALLOC_MAX_SIZE before attempting the allocation. Fixes: 22a1ffea5f80 ("block: add IOC_PR_READ_KEYS ioctl") Reported-by: syzbot+660d079d90f8a1baf54d@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D660d079d90f8a1baf54d Signed-off-by: Deepanshu Kartikey --- block/ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/ioctl.c b/block/ioctl.c index 61feed686418..3e9e4257569f 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -443,7 +443,7 @@ static int blkdev_pr_read_keys(struct block_device *bde= v, blk_mode_t mode, return -EFAULT; =20 keys_info_len =3D struct_size(keys_info, keys, read_keys.num_keys); - if (keys_info_len =3D=3D SIZE_MAX) + if (keys_info_len =3D=3D SIZE_MAX || keys_info_len > KMALLOC_MAX_SIZE) return -EINVAL; =20 keys_info =3D kzalloc(keys_info_len, GFP_KERNEL); --=20 2.43.0